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Volume 51, 1919
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Art. XVIII.—Notes on the Autecology of certain Plants of the Peridotite Belt, Nelson: Part I—Structure of some of the Plants (No. 2).*

[Read before the Otago Institute, 10th December, 1918; received by Editor, 30th December, 1918; issued separately, 26th May, 1919.]

10. Rubus australis Forst.

Growth-form.—“A tall climber, reaching the tops of the highest trees; stems stout, woody at the base; branches slender, drooping, armed with scattered recurved prickles. Leaves 3–5-foliolate or rarely pinnate, with 2 pairs of leaflets and a terminal one; leaflets coriaceous, glabrous, very variable in size and shape, 2–5 in. long, ovate-oblong or ovate-lanceolate to linear-oblong or almost linear, acute or acuminate, truncate or cordate at the base, sharply serrate; petioles and midribs armed with recurved prickles.”

Anatomy.

Leaf.—The upper epidermis consists of small cells, which are oval or rectangular in transverse section. These cells have their walls somewhat thickened, and there is a thick smooth cuticle. There are no stomates on the upper surface.

The lower epidermis is formed of small more or less squarish cells. These cells have their walls slightly thickened, and there is a cuticle, which is not, however, as thick as on the upper face of the leaf. Stomates are frequent on the lower surface. The guard-cells are small, and are at the same level as the epidermal cells; the stomates are protected by guard-cell ridges.

Beneath the upper epidermis there is a hypoderma consisting of large rectangular cells with thickened walls.

The chlorenchyma is differentiated. The palisade tissue is composed of 3 layers of thin-walled cells containing fairly large chloroplasts. The 2 outer layers are very compact, but there are air-spaces between the cells of the inner layer. The spongy tissue consists of rather small, irregular, thin-walled cells, which are loosely arranged.

The midrib is prominent. Above the xylem there is a group of large cells with thickened lignified walls. The xylem contains vessels of large diameter. Beneath the phloem there is a zone of sclerenchyma, in which the cells are small and have thick walls and small cell-cavities. Below this zone there are some large cells with thickened lignified walls. Above the midrib the epidermal cells are much smaller, and a few of them are produced into unicellular hairs, with thick walls which are not cutinized. Above and below the midrib there is collenchyma.

Stem.—The epidermis consists of very small dome-shaped cells with their lateral and their external walls cutinized. The cuticle is uneven, and is very thick.

[Footnote] * For No. 1 see Trans. N.Z. Inst., vol. 50, pp. 230–43, 1918.

[Footnote] † T. F. Cheeseman, Manual of the New Zealand Flora, 1906. (See No. 1 of these Notes, loc. cit., p. 231.)

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The cortex consists of 6–9 layers of cells with thick walls. This tissue is very compact. The endodermis is well marked; it is composed of two distinct zones; adjoining the cortical cells there is a single layer of fairly large cells containing starch. Then comes a ring, 1–2 cells wide, of large rectangular cells with suberized walls.

The pericycle fibres form a wide band. The fibres are of small diameter, and are closely packed. The walls are thick, and the lumen small.

The phloem forms a wide band of small-celled elements. The xylem consists for the most part of vessels of large diameter, but there are also wood-fibres. The medullary rays are 2–3 cells wide, and the cells have lignified walls.

The pith is solid, and consists of round and polygonal cells, which vary considerably in size. The walls are thickened, lignified, and pitted.

11. Viola Cunninghamii Hook. f.

Growth-form.—A small tufted herb. It has a somewhat woody root-stock, creeping below and tufted above. The leaves are glabrous, and are tufted on the top of the rootstock, or on short branches springing from it; they are about ½ in. long, triangular-ovate, truncate at the base, obtuse and obscurely crenate; the petioles are ½–1¼ in. long, and are occasionally pubescent. The stipules are adnate to the base of the petiole.

Anatomy.

Leaf.—The upper epidermis consists of large oval cells with thin walls. A thin cuticle is present. The lower epidermis is similar, except that the cells are smaller. Stomates are found on both surfaces, but are more numerous on the lower. The guard-cells are small, and at the same level as the epidermal cells. There are no guard-cell ridges.

The chlorenchyma is differentiated. The palisade tissue consists of 2 rows of cells, the cells of the outer layer being deeper than those of the inner. There are fairly large intercellular air-spaces between the palisadic cells. The spongy tissue consists of rounded or irregular cells fairly loosely arranged, so that there are numerous intercellular air-spaces. All the chlorenchymatous cells contain moderately large chloroplasts.

The vascular system of the leaf is not very well developed. In the bundle there is only a small amount of lignified tissue, and there is a good deal of parenchyma. The bundle is surrounded by a rather poorly defined sheath of small, thin-walled, colourless parenchymatous cells.

Between the bundle-sheath and the lower epidermis, and below the upper epidermis, there is some colourless, thin-walled, parenchymatous tissue, which forms an aqueous tissue. There are only minute air-spaces between these cells. Below the bundle the epidermal cells are smaller and the cuticle is somewhat thicker.

Stem.—The epidermis consists of small oval or rectangular cells, which have thin walls and a thin cuticle.

The cortex is composed of large, closely packed, thin-walled, more or less rounded parenchymatous cells. There are very small intercellular air-spaces. Many of the cortical cells contain small starch-grains, and a few contain crystal aggregates (sphaero-crystals) of calcium oxalate.

The endodermis is well marked, and consists of large cells with thin suberized walls.

The phloem forms a wide continuous band; the sieve-tubes are of fairly large diameter, and associated with them is parenchyma. The xylem

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forms a band of tissue only slightly wider than the phloem. The vessels are numerous and of large diameter, and their walls are not very thick. Separating the rows of vessels are wood-fibres.

The pith is solid, and consists of large thin-walled cells which are closely packed together, so that there are only very small air-spaces at the corners Near the xylem the pith-cells are smaller.

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Fig. 1.—Hymenanthera dentata var. alpina. Entire young plant (× ½).

12. Hymenanthera dentata R. Br. var. alpina Kirk.

Growth-form.—This plant is a low, much-branched, rigid shrub, 1–2 ft. high, with tortuous or zigzag interlacing branches; the branches are densely compacted, and end in stout spines. The leaves are alternate or fascicled, thick and coriaceous, ⅙–⅓ in. long, linear-obovate, with entire or irregularly lobed margins. The petioles are very short. A young plant is illustrated in fig. 1.

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Anatomy.

Leaf (fig. 2).—The upper and the lower epidermis consist of large more or less squarish cells with thin walls. There is a thick cuticle on both surfaces. Stomates are found on both faces of the leaf. The guard-cells are level with the upper surface of the epidermal walls, but are below the cuticle. The guard-cells have thickened walls, and the stoma is protected by the guard-cell ridges.

The chlorenchyma is rather feebly differentiated. The palisade tissue consists of 4–5 rows of oval cells with very slightly thickened cell-walls, and containing a small number of large chloroplasts. The 2 outer layers of palisadic tissue are compact, but the inner ones are not so closely arranged. There is also palisade tissue on the lower surface of the leaf. Here it is only 1–2 rows of cells. The spongy tissue consists of rather irregular loosely arranged cells, so that there are large intercellular air-spaces. These cells also contain large chloroplasts.

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Fig. 2.—Hymenanthera dentata var. alpina. Transverse section of lamina of leaf (× 230). a, thick cuticle; b, palisade parenchyma; c, bundle-sheath; d, xylem; e, phloem; f, guard-cell ridge.

The vascular bundle is of the usual dicotyledonous type; the amount of lignified tissue in the xylem is small. Surrounding the bundle is a sheath of large thin-walled cells, which are practically devoid of chloroplasts.

Stem (fig. 3).—The cork forms a wide band, and consists of fairly large cells with thickened walls. Then comes the phellogen of thin-walled rectangular cells.

The cortex forms a layer of tissue 12–14 cells deep; its cells are oval and have thickened walls. There are numerous intercellular air-spaces, most of which are, however, small. Drops of oil are found in the cortical cells.

The pericycle fibres form small isolated groups. The cells are small and have very thick walls, so that the cell-cavities are almost obliterated.

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The phloem contains a fairly large amount of parenchyma. The xylem elements are very regularly arranged. The xylem contains only a very small number of tracheae; it is composed almost entirely of wood-fibres and wood-tracheides. The fibres and tracheides have fairly thick cell-walls. The tracheides are pitted.

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Fig. 3.—Hymenanthera dentata var. alpina. Transverse section of stem (× 176). a, cork; b, oil in cortical cells; c, pericycle fibres; d, phloem; e, medullary ray; f, pith with starch in cells.

The medullary rays are fairly numerous; they are uniseriate and have thickened lignified walls. The cells contain starch.

The pith is solid, and consists of very closely packed rounded or polygonal cells with thickened lignified walls. These cells contain numerous starch-grains.

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13. Pimelea Suteri T. Kirk.

Growth-form.—“A small much-branched shrub, 4–12 in. high; branches spreading or suberect, often tortuous; the younger ones sparingly pilose with rather long straight silky hairs; bark, dark red-brown or black. Leaves crowded, shortly petiolate or nearly sessile, erecto-patent, about ⅓ in. long, narrow linear-lanceolate, subacute, coriaceous, concave above, both surfaces glabrous or rarely with a few lax hairs, margins and apices ciliated with long straight hairs.”

Anatomy.

Leaf (Fig. 4).— gives a diagrammatic view of the transverse section, while fig. 5 shows a portion of the section in detail.

Both the upper and the lower epidermis consist of narrow rectangular cells, which have their lateral and internal walls slightly thickened and the external ones considerably thickened. There is a cuticle on both surfaces. Stomates are found on both surfaces, and are slightly sunken below the thickened epidermal walls. The guard-cells have thickened walls, and the opening is protected by guard-cell ridges.

Below the epidermis, on both surfaces, there is a hypoderma of very large colourless cells: these form mucilage-sacs.

The chlorenchyma is differentiated. The palisade tissue is found on both sides of the leaf. It consists of 2–3 rows of cells, these being somewhat larger in the upper than in the lower palisade tissue. The walls are thin and contain numerous chloroplasts. Some of the cells contain tannin. The air-spaces in this tissue are small. Beneath the stomates the layer of mucilage-cells is interrupted by the palisade tissue. Beneath each stoma there is a fairly large cavity. The spongy tissue consists of somewhat irregular cells with numerous chloroplasts. The air-spaces are small. Most of the cells contain tannin.

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Fig. 4.—Pimelea Suteri. Transverse section of leaf (diagrammatic) (× 36). a, epidermis; b, mucilage-cells; c, chlorenchyma.
Fig. 5. — Pimelea Suteri. Transverse section of leaf (× 175). a, cuticlo; b, epidermis; c, mucilage-sac; d, palisade parenchyma, e, bundle-sheath; f, xylem; g, phloem; h, sclerenchyma; i, stoma.

Surrounding the vascular bundle there is a sheath of thin-walled paren-chymatous cells which contain tannin. The xylem is formed of wood-fibres and tracheides of small diameter and with thickened walls. The xylem is

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very regularly arranged. The amount of phloem is small; the phloem parenchyma cells contain tannin. Beneath the phloem there is some stereome, consisting of small cells with very thick walls and small lumen.

Stem (fig. 6).—The cork forms a wide band 20–30 cells wide. The cells are large and have thick walls.

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Fig. 6.—Pimelea Suteri. Transverse section of stem (× 175). a, cork; b, cortex; c, fibres; d, phloem; e, cambium; f, trachea; g, pith.

The cortex consists of large oval cells, which have thick, somewhat mucilaginous, cell-walls. The tissue is compact, only small air-spaces being present. The cells of the outer part of the cortex contain tannin, and those of the inner part contain small drops of oil. There are numerous small groups of pericycle fibres, composed of very small cells with thick walls small cavities.

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The phloem is a practically continuous band (only interrupted by a few uniseriate medullary rays). The xylem contains numerous tracheae, but the bulk of the xylem is occupied by tracheides and by wood-fibres of small diameter and with small lumen.

The medullary rays are few; they are uniseriate, and the cells have lignified walls. The amount of pith is small; it consists of small roundish cells, most of which contain tannin.

14. Metrosideros robusta A. Cunn.

“Usual Growth-form.—” A tall and stout forest-tree, 60–80 ft. or even 100 ft. high; trunk irregular, 3–8 ft. diameter or more; branches spreading, forming a huge rounded head; branchlets 4-angled, puberulous. Leaves decussate, 1–1½ in. long, elliptic-oblong or ovate-oblong or elliptic-lanceolate, obtuse, glabrous, very coriaceous; petioles short, stout, glabrous or puberulous.”

Mineral Belt Growth-form.—A small, rounded, compact bush.

Anatomy.

Leaf (fig. 7.—The upper epidermis consists of small cells with thin walls, but with a very thick cuticle. The cells of this layer contain small drops of oil. The cells of the lower epidermis are smaller than those of the upper, and the cuticle is thinner and ridged. On both surfaces of the leaf are numerous large oil-glands; they are more numerous on the lower surface

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Fig. 7.—Metrosideros robusta. Transverse section of leaf (x 110). a, thick cuticle; b, epidermis; c, hypoderma; d, palisade tissue; e, xylem; f, phloem; g, oil-gland.
Fig. 8.—Metrosideros robusta. Transverse section of stem (x 24). a, thick cuticle; b, cortex; c, pericycle fibres; d, phloem; e, xylem.

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Stomates are confined to the lower surface. The guard-cells are small, with thickened walls, and the stomates are protected by guard-cell ridges.

Below the epidermis there is a well-marked hypoderma; the upper hypoderma consists of 1 layer of large cells with thick walls, while the lower, a layer 1–2 cells thick, is composed of smaller cells, also with thick walls. All the hypodermal cells contain tannin.

The chlorenchyma is differentiated. The palisade tissue consists of 3 compact rows of cells, most of which contain tannin. The spongy tissue is composed of very irregular cells loosely arranged, so that there are large intercellular air-spaces. These cells have thickened walls, and many of them contain tannin.

The bundle-sheath consists of small, oval, thin-walled cells which contain tannin. Above the xylem and below the phloem there is stereome, consisting of small cells with thick walls, the cells adjacent to the phloem being smaller than those above the phloem. The xylem consists of wood-fibres and vessels of small diameter; these are arranged regularly in rows, which are separated by rows of small, thin-walled, parenchymatous cells which contain tannin.

Stem (fig. 8).—Fig. 8 is a diagrammatic view of a young stem.

The epidermis is composed of very small thin-walled cells; there is a thick cuticle.

The cortex consists of small thin-walled cells, more or less rounded in shape, the outer layers containing small chloroplasts. Most of the cortical cells contain tannin.

The pericycle fibres form a continuous ring round the phloem. The fibres are of small diameter, and their walls are very thick.

All the phloem parenchyma cells contain tannin, as do also the cells of the medullary rays and of the pith. The cambium is well marked, consisting of 3 rows of small regular cells. The xylem consists of vessels of fairly large diameter, and of wood-fibres of small diameter. The medullary rays are uniseriate, and their cells have thickened lignified walls.

The pith consists of rather small roundish cells which are closely arranged together. Some of the pith-cells contain crystal-aggregates of calcium oxalate.

15. Metrosideros lucida A. Rich.

Usual Growth-form.—“Usually a tall erect branching tree 30–60 ft. high, but often dwarfed to a small bush in subalpine or exposed localities; bark pale, papery; branchlets and young leaves silky. Leaves 1½–3 in. long, elliptic-lanceolate or lanceolate, acuminate, very coriaceous, pale glossy-green above, dotted with oil-glands beneath, narrowed into a short stout petiole.”

Mineral Belt Growth-form.—A small, rounded, woody bush, with leaves ¾–1½ in. long.

Anatomy.

The structure of both stem and leaf corresponds with that in M. robusta

16. Epilobium pedunculare Hook. f.

Growth-form.—A small herb, with slender prostrate branches 2–6 in. long, which root at the nodes and are sparingly branched. The branches are almost glabrous. The leaves are opposite, ½–¼ in. long, orbicular-ovate, rounded at the apex, fleshy and entire, and with a very short petiole.

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Anatomy.

Leaf.—The upper and the lower epidermis consist of more or less rectangular cells with thin walls, except for the external ones, which are slightly thickened. A thin cuticle is present. Stomates are equally numerous on both surfaces; the guard-cells are small, and level with the surface.

The chlorenchyma is differentiated. The palisade tissue consists of 3′ layers of cells with thin walls, and containing numerous chloroplasts; these cells are closely packed together. The spongy tissue is composed of more or less irregular thin-walled cells, forming a compact tissue with only very small intercellular air-spaces. The chloroplasts are not nearly as abundant in this tissue as in the palisadic. At intervals in the mesophyll there are canals which are surrounded by a layer of epithelial cells. Raphides of calcium oxalate are found in the mesophyll.

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Fig. 9.—Epilobium pedunculare. Transverse section of stem (× 36). a, epidermis; b, cortical chlorenchyma; c, colourless cortex; d, endodermis; e, phloem; f, xylem; g, pith with starch; k, pith without starch.
Fig. 10.—Epilobium pubens. Transverse section of stem (× 36). a, epidermal hair; b, cortical chlorenchyma; c, colourless cortex; d, endodermis; e, phloem; f, xylem; g, pith with starch; h, pith without starch.

The vascular bundles are small, and contain only a small amount of lignified tissue. Below the midrib there are small more or less rounded cells, which contain a very few chloroplasts. This forms a water-tissue. In the vicinity of the vascular bundles the lower epidermal cells are smaller and have thicker walls.

Stem (fig. 9).—The epidermis is composed of small cells, which in transverse section are squarish or round. These cells have thickened walls, and there is also a cuticle, which is, however, only thin. Some of the epidermal cells are produced into thin-walled unicellular hairs, which contain protoplasm. Stomates are present, but are not numerous; the guard-cells are small, and level with the surface, as in the leaf.

The cortex forms a fairly wide band, about 9 cells wide. The outer portion consists of small cells with thickened walls, and containing a few chloroplasts. The inner part of the cortex consists of larger roundish or polygonal thin-walled cells which are compactly arranged, so that there are only very small air-spaces. These cells contain starch-grains. The endodermis is well defined; it consists of a single layer of large oval or rectangular cells with suberized walls.

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The phloem forms a continuous ring round the xylem; the phloem parenchyma cells contain small starch-grains. The xylem forms a band only slightly wider than the phloem; it consists of vessels and of wood-fibres.

The pith consists of thin-walled more or less circular cells, with small air-spaces between them. The cells adjacent to the xylem are small, and contain starch. There is a large pith-cavity.

17. Epilobium pubens A. Rich.

Growth-form.—The plant is a small herb, with stems 3–8 in. high, slender, simple, decumbent and woody at the base, erect above, terete, uniformly clothed with a short fine pubescence. The leaves are alternate, ¼–½ in. long, ovate, obtuse, narrowed into slender petioles, pubescent on both surfaces, thin and toothed.

Anatomy.

Leaf.—This is thinner than in E. pedunculare, and the veins are more prominent. The upper epidermis is formed of large cells, more or less rectangular in transverse section; the walls are thin, except the external ones, which are somewhat thickened. A thin cuticle is present. Some of the epidermal cells are produced into unicellular hairs, which contain protoplasm and which have thin cutinized walls. The lower epidermis is similar to the upper, except that the cells are smaller. Stomates are confined to the lower surface, where they are very numerous. The guard-cells are small, and are slightly raised above the surface of the epidermis.

The palisade tissue is composed of 2 rows of thin-walled cells closely packed together, so that there are only very small intercellular air-spaces. These cells contain chloroplasts, which are smaller and much less numerous than in E. pedunculare.

The spongy tissue consists of about 4 rows of more or less rounded thin-walled cells, which are somewhat loosely arranged. Raphides of calcium oxalate are present in the mesophyll. Many of the mesophyll cells, especially those of the palisade tissue, contain drops of oil. Canals are present, as in E. pedunculare, but they are more numerous.

The vascular bundles are larger than in E. pedunculare, and the xylem contains more lignified elements. Around and below the bundles is a water-storage tissue, which consists of thin-walled, polygonal, closely packed, colourless cells.

Stem (fig. 10).—The epidermis consists of small oval or rectangular cells, with all walls thickened and with a fairly thick cuticle. Many of the epidermal cells are produced into straight unicellular hairs, which contain protoplasm and have thin cutinized walls. Stomates are not numerous; they are level with the epidermis, and the guard-cells are small.

The outer layers of the cortex (about 3 rows of cells) consist of oval cells, with their walls slightly thickened and with small intercellular airspaces. These cells contain a few chloroplasts, and some of them contain oil. The rest of the cortex consists of larger more irregular cells. The endodermis is well marked, and is composed of a layer of large cells with thin suberized walls.

The phloem forms a narrower band than in E. pedunculare, and the xylem is wider, but is of the same type.

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18. Anisotome filifolium (Hook. f.) Cockayne and Laing.

Growth-form.—This is a slender aromatic herb. The stems are about 4–8 in. high, smooth and striate. The leaves are 3–6 in. long, and are flaccid; the blades are very variable in size, and are ternately divided into narrow filiform acute segments ½–1½ in. long. The petioles are long, slender, sheathing at the base; the sheaths are short, broad, and membranous.

Anatomy.

Leaf (fig. 11).—The epidermal cells are large, those of the upper epidermis being a little larger than those of the lower; the cell-walls are thickened, the external walls being very much thicker than the lateral or internal ones. There is a cuticle on both surfaces. Stomates are found on both surfaces, being somewhat more numerous on the lower than on the upper face. The stomates are raised above the epidermal cells, but not above their thickened walls. The guard-cells have thickened walls, and the stoma is protected by guard-cell ridges.

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Fig. 11.—Anisotome filifolium. Transverse sections of leaf (× 175). a, cuticle; b, thickened epidermal walls; c, stoma; d, oil-duct; f, xylem; g, phloem; h, spongy tissue.

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Fig. 12.—Anisotome filifolium. Transverse section of peduncle (diagrammatic) (× 175). a, sclerenchyma; b, cortex; c, pericycle fibres; d, xylem; e, lignified pith; f, pith-cavity.

The chlorenchyma is differentiated into palisade and spongy tissue. The palisade tissue is composed of 1–4 rows of cells (1 near the margin, 4 in the centre of the lamina). The cells are large and elongated, thin-walled and compactly arranged, and contain abundant chloroplasts. The palisadic tissue passes gradually into the spongy, which consists of rather irregular cells with thin walls and containing abundant chloroplasts. This tissue is loosely arranged, so that there are large air-spaces. There are large air-spaces beneath the stomates. Above the lower epidermis there is a layer of chlorenchymatous cells, which are smaller, more regular, and are closely arranged.

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In the leaf there are 3 larger veins and 2 very small ones. They are surrounded by a sheath of small thin-walled parenchymatous cells, which contain only a small number of chloroplasts. Below each bundle there is an oil-duct, surrounded by 6–8 small epithelial cells. The amount of lignified tissue in the bundle is small.

Peduncle (figs. 12 and 13).—Fig. 12 gives a schematic view of the transverse section. In each ridge there is a group of lignified cells, and the whole of the central part is lignified. Fig. 13 shows the structure in detail.

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Fig. 13.—Anisotome filifolium. Transverse section of peduncle (× 175). a, cuticle; b, stoma; c, chlorenchyma; d, oil-duct; e, aqueous tissue; f, pericycle fibres; g, phloem; f, cambium; i, xylem; j, pith.

The epidermis consists of small cells, which are squarish above the ridges and are rectangular or oval in the furrows. The walls of these cells are thickened and lignified, and there is a cuticle. Stomates are found in the furrows. They are level with the epidermis; the guard-cells have thickened walls, and the opening is protected by guard-cell ridges.

Beneath the epidermis in the ridges there is a mass of sclerenchyma: this is composed of small cells with very thick walls and small lumen. Under the epidermis in the furrows are about 5 rows of chlorenchymatous cells. This band is also present under the sclerenchyma in the ridges; here it is about 2 cells wide. The outermost layer of this band of tissue consists of cells which are slightly elongated in a direction parallel with the surface, and which have slightly thickened walls. The rest of the chlorenchymatous tissue consists of more or less rounded cells with thinner walls. This tissue is very compact.

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Inside this zone of tissue there is a band of colourless cortical tissue: this is composed of large roundish or polygonal cells, forming a compact tissue with only very small intercellular air-spaces. These cells are colourless, and form a water-storage tissue.

Above the phloem of the bundles there is a small group of pericycle fibres with thick walls and small cavities. Above the fibres there is a duct of large diameter, lined by about 8 epithelial cells. The phloem is a narrow band of small elements; the cambium, 2 rows of cells, can be clearly seen. The xylem consists of vessels of fairly large diameter and of xylem parenchyma.

All the ground-tissue internal to the water-tissue is lignified. The 3 or 4 rows of cells adjacent to the water-tissue are small, thick-walled, and compactly arranged. Passing inwards from this the cells become larger and their cell-walls thinner, but they are still lignified. There are large intercellular air-spaces where 3 or more cells meet. The stem is hollow.

19. Anisotome aromaticum Hook. f. var.

[The section below cannot be correctly rendered as it contains complex formatting. See the image of the page for a more accurate rendering.]

Growth-form.—A small aromatic herb, matted and depressed, 1—2½ in high. The root is stout, long, and tapering. The stem is simple. The leaves are all radical, numerous, 1—6 in. long; the blade is linear and pinnate; the leaflets are in 6—12 pairs, 1/5—½ in. long, more or less incised; the lobes end in a bristle-like point. The petiole is short, stout, and broadly sheathing at the base.

Anatomy.

Leaf (figs. 14, 15).— Fig. 14 shows the form of the leaf, and fig. 15 gives a diagrammatic view of the transverse section.

The upper epidermis consists of fairly large squarish cells with thick walls. A thick cuticle is present, forming a minute papilla above each cell. There are no stomates on the upper surface. The lower epidermis consists of smaller cells than the upper; the walls are thickened, and there is a thick smooth cuticle. Stomates are confined to the lower surface, where they are slightly raised above the epidermis. The stoma is protected by guard-cell ridges. Beneath the upper epidermis there is a hypo-derma, formed of thick-walled cells like those of the upper epidermis; these cells contain a few small chloroplasts.

The palisade tissue is formed of 2 rows of cells, which are small, thin-walled, closely packed together, and contain numerous chloroplasts. The spongy tissue consists of irregular cells, with the walls slightly thickened; they are loosely arranged, and contain numerous chloroplasts. The meso-phyll cells just above the lower epidermis are much smaller, are rounded, and are closely packed together.

The vascular bundles are surrounded by a sheath of thin-walled paren-chymatous cells, which contain a very few chloroplasts. The amount of lignified tissue in the xylem is small. Above the xylem and below the phloem there are ducts lined by a single layer of small epithelial cells. The duct below the phloem is much larger in diameter than that adjacent to the xylem.

Peduncle (fig. 16.)—The epidermis consists of very small rounded or squarish cells, with thickened walls and a fairly thick cuticle.

The outer 3 or 4 rows of cortical cells are small round cells, with very thick walls and no air-spaces between the cells. The remaining part of

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the cortex consists of larger cells, with thinner walls and small intercellular spaces between the cells. All the cortical cells contain chloroplasts.

Above each group of phloem there is a wide oil-duct surrounded by epithelial cells. The phloem elements are small, but the width of phloem band is much greater than in A. filifolium. The xylem is divided into 2 parts: (1) next to the phloem there is a band of wood-fibres; (2) a group of 5—10 vessels with xylem parenchyma.

The pith is composed of large thin-walled cells, but in the outer part the cells are smaller, and their walls are thicker and are lignified.

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Fig. 14.—Anisotome aromaticum. Entire leaf (×½). a, sheathing base.
Fig. 15.—Anisotome aromaticum. Transverse section of leaf (× 36). a, cuticle; b, hypoderma; f, palisade parenchyma; d, spongy parenchyma; e, oil-duct; f, xylem; g, phloem.
Fig. 16.—Anisotome aromaticum. Transverse section of peduncle (× 36). a, cuticle; b, collenchyma; c, cortex; d, oil-duct; e, penricle fibres; f, phloem; g, xylem.

20. Griselinia littoralis Raoul.

Usual Growth-form.—“A round-headed tree, 30—50 ft. high; trunk short, irregular, gnarled or twisted, 2—5 ft. diameter; bark rough, furrowed. Leaves 1—4 in. long, ovate or oblong-ovate, rounded at the tip,

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less unequal-sided at the base than in G. lucida, and sometimes almost symmetrical, pale yellowish-green, thick and coriaceous; veins obscure; petiole slender, ½—1 in. long.”

Mineral Belt Growth-form.—-A woody shrub attaining a height of about 6 ft.

Anatomy.

Leaf.—The structure of the leaf has been described and figured by Miss Suckling (Trans. N.Z. Inst., vol. 46, pp. 186—87, 1914). My specimens agree in leaf-structure with her description of the leaf of a well-illuminated tree, except that the hypodermal cells are larger than she figures.

Stem.—The epidermis is composed of small oval cells, which contain oil and which have thickened cell-walls, and in addition there is a thick uneven cuticle which is of a light-green colour.

The cortex is wide; the cells are oval and thick-walled. In the outer part the cortex is very compact, but in the inner part there are air-spaces between the cells.

The pericycle fibres do not form a continuous band round the phloem. The fibres are of small diameter, and their walls are so much thickened that the cell-cavities are almost obliterated.

The phloem forms a wide continuous band. The xylem consists of vessels and of wood-fibres, both of which are of fairly large diameter.

The medullary rays are nearly all uniseriate, with thickened lignified cell-walls. These rays are numerous There are also a few multiseriate rays 2—4 cells wide.

The pith is formed of round cells with thickened lignified walls, and containing abundant starch. Small intercellular air-spaces are present.

21. Gaultheria antipoda Forst. var.

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Growth-form.—An erect much-branched rigid shrub 6—16 in. high. The branches are stout, sometimes glabrous but usually more or less clothed with a brownish pubescence. The leaves are alternate, shortly petiolate, about 2/5 in. long, orbicular, obtuse, bluntly serrate, and very coriaceous. The leaves are glabrous, except the petioles, which are pubescent.

Anatomy.

Leaf.—The upper epidermis consists of small rectangular cells. A thick cuticle is present. The lower epidermal cells are smaller than the upper, and the cuticle is not so thick. Stomates are confined to the lower surface, and are protected by guard-cell ridges. Beneath the epidermis there is a hypoderma—1 layer of large cells with their walls slightly thickened.

The palisade tissue is composed of 3 rows of thin-walled cells, which contain numerous chloroplasts arranged along the lateral walls. There are no air-spaces between these cells. The spongy tissue consists of irregular loosely arranged thin-walled cells which contain numerous chloroplasts.

The vascular bundles are numerous. Each is more or less surrounded by stereome—small polygonal cells with very thick walls and small lumen. The parenchymatous elements of the bundle contain tannin.

Stem.—The epidermis is composed of small roundish cells with thickened walls and with a thick cuticle. Some of the epidermal cells are produced into long unicellular hairs, with thickened and slightly cutinized walls.

In the section of an older stem the corky layer is thick, and is composed of very small cells with thick walls

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The cortex consists of large oval cells with thick walls. The outer region of the cortex is very compact, but the inner part has the cells loosely arranged

The phloem is of the usual type. The xylem is composed of numerous vessels of moderately large diameter, and of wood-fibres with thick cell-walls.

The medullary rays are numerous and are uniseriate; the cells have their walls thickened and lignified. All the medullary-ray cells contain tannin.

The pith is composed of two kinds of cells: (1) Small more or lees polygonal cells with thick walls, and containing tannin; (2) much larger thin-walled cells: in these the walls are only slightly lignified and the cells do not contain tannin.

22. Dracophyllum Urvilleanum A. Rich.

Growth-form.—A much-branched shrub 3—5 ft. high; the branches are slender and erect, with black or dark-brown bark. The leaves are erect, slender, 1—3½ in. long. The sheathing base is ⅛—⅛ in. broad, brown, striate, and membranous; the blade is very narrow and coriaceous.

Anatomy.

Leaf (figs. 17, 18).—The upper epidermus consists of small roundish cells with thickened slightly lignified walls. A thick cuticle is present. Some of the epidermal cells are produced into short stiff unicellular hairs, which have extremely thick cutinized walls. The lower epidermis consists of slightly smaller cells than does the upper: these cells also have thickened lignified walls; and there is a thick cuticle. Stomates are found on both surfaces, but they are much more numerous on the lower surface. The guard-cells have thickened walls, and the opening is protected by guard-cell ridges.

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Fig. 17.—Dracophyllum Urvilleanum. Transverse section of leaf (× 48). a, cuticle; b, stereome; c, vascular bundle.

The chlorenchyma is homogeneous; it is a very compact tissue composed of large cells with their walls slightly thickened. Oil and tannin are present in many of the mesophyll cells.

There are 7—9 vascular bundles; all the xylem elements are lignified, and the phloem parenchyma cells contain tannin.

Surrounding each vascular bundle there is a large mass of stereome; 3—5 of these bands of sclerenchyma extend right across the leaf, from one epidermis to the other. The groups around the bundles nearer the margins of the leaf are much smaller. The sclerenchymatous cells are 4—6-sided, and are very compactly arranged. The cells have very thick walls and minute lumen.

In the margins of the leaf there are 1—3 layers of larger sclerenchymatous cells.

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Fig. 18.—Dracophyllum Urvilleanum. Transverse section of leaf (× 230). a, bristle; b, thick cuticle; c, epidermis; d, stereome; e, phloem; f, xylem; g, stoma.
Fig. 19.—Dracophyllum Urvilleanum. Transverse section of sheathing leaf-base (X 36). a, cuticle; b, mesophyll; c, stereome; d, vascular bundle; e, lignified tissue.
Fig. 20.—Dracophyllum Urvilleanum. Transverse section of margin of leaf-base (× 175).
Fig. 21.—Dracophyllum Urvilleanum. Transverse section through middle of sheath (× 175). a, cuticle; b, epidermis; c, stereome; d, vascular bundle.

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Sheathing Leaf-base (figs. 19—21).—This resembles the leaf in general structure, but differs in a few details: (1.) The cells of the outer epidermis are elongated at right angles to the surface. Like the epidermal cells of the leaf, they have very thick walls, but here they are not lignified. The inner epidermis is composed of roundish cells, with thickened lignified walls. (2.) There is a cuticle on both surfaces, but it is not so thick as in the leaf. (3.) Near the margins of the leaf all the cells, except those of the outer epidermis, have thickened lignified walls. (4.) There is a hypoderma of lignified cells on the upper surface.

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Fig. 22.—Dracophyllum Urvilleanum. Transverse section of stem (× 175). a, thick cuticle; b, epidermis; c, dead cortex; d, pericycle fibres; e, suberized tissue; f, phloem; g, medullary ray; h, xylem; i, air-passage; j, pith.

Stem (fig. 22).—On the outside are the dead epidermal and cortical cells. The epidermal cells are small, thick-walled, and have a very thick cuticle. The cortical cells are irregular and thick-walled; their walls are suberized and also lignified.

Inside this layer are some fibres which form a more or less continuous band of small cells with very thick walls and small lumen.

Then comes a band of corky tissue; this is a moderately wide band, and is composed of small regular thick-walled cells.

The phloem is also a fairly wide band; the phloem elements are very regularly arranged, and the parenchymatous cells contain tannin. The

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xylem consists of vessels of small diameter with thickened walls and of wood-fibres, with very thick walls and small cell-cavities.

Medullary rays are numerous and are uniseriate; they have thickened lignified walls, and contain tannin. A few of the cells contain starch. The pith is wide, and is solid. The cells are small, and have thickened lignified walls. Many of these cells contain tannin. The cells are loosely arranged, with large air-spaces between them.

23. Dracophyllum rosmarinifolium R. Br.

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Growth-form.—This plant is a depressed or prostrate much-branched rigid woody shrub, 3–18 in. high; the branches are stout, spreading, leafy at the tips. The leaves are erect, rigid, and curved, ¼—¾ in. long; the sheathing base is short, ⅛ in. wide; the blade is 1/20 in. wide at the base, very thick and coriaceous, convex at the back and flat in front; the tip is trigonous.

Anatomy.

Leaf (fig. 23).—The structure of the leaf is the same as in D. Urvilleanium, the only differences being that the leaf is narrower and thicker. There are 3 large bundles and 4 smaller ones. Tannin idioblasts in the mesophyll are more abundant than in D. Urvilleanum.

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Fig. 23.—Dracophyllum rosmarinifolium. Transverse section of leaf (diagrammatic) (X 36). a, bristles; b, stereome; c, vascular bundle; d, mesophyll.
Fig. 24.—Pentachondra pumila. Transverse section of leaf (diagrammatic) (X 36). a, cuticle; b, epidermis; c, palisade tissue; d, spongy tissue; e, vascular bundle.
Fig. 25.—Pentachondra pumila. Transverse section through upper epidermis (X 175). a, cuticle; b, thickened cell-wall; c, cell-cavity.
Fig. 26.—Pentachondra pumila. Transverse section of lower epidermis (X 175). a, stoma.
Fig. 27.—Pentachondra pumila. Transverse section of stem (diagrammatic) (X 36). a, cortex; b, cortex; c, radiating lines of suberized cells; d, phloem; e, xylem.

Stem.—On the outside there are dead brown cells, the remains of the old epidermis, cortex, and pericycle fibres.

The cork forms a wide zone of small compactly arranged cells. The cells have thick walls, which in the inner part of the zone are lignified as well as suberized.

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The cortex is a very narrow band of tissue, composed of small round thick-walled cells which contain tannin and which are closely packed together, so that there are no air-spaces.

The phloem also is a narrow band of tissue. The phloem parenchyma cells contain tannin. The xylem is of the same type as in D. Urvilleanum. In addition to the numerous uniseriate medullary rays, there are 3 or 4 wide multiseriate rays. The cells of the latter do not have lignified walls, but they contain tannin. There are more wood-fibres with thickened walls in the wood of this plant than in D. Urvilleanum.

The pith is solid and like that of D. Urvilleanum, except that tannin is more abundant.

24. Pentachondra pumila R. Br.

Growth-form.—This plant is a much and closely branched dwarf shrub, 2–6 in. high; stems stout, woody, and procumbent; the branches are ascending, and are covered by a very dark-brown bark. The leaves are numerous, crowded, suberect, ⅛ in. long. oblong to ovate-oblong, and with a callous tip.

Anatomy.

Leaf (figs. 24–26).—In shape the transverse section is like that of the leaf of Dracophyllum Urvilleanum, but in the latter the convex surface is the lower, and in this plant it is the upper.

The upper surface consists of large regular cells, which are slightly elongated at right angles to the surface of the leaf. The lateral and internal walls of these cells are thin, but the external walls are very much thickened. In addition there is a very thick rough cuticle. The lower epidermis consists of small regular cells. Their walls are only slightly thickened; and there is a thick cuticle, which is not, however, as thick-as on the upper surface of the leaf. Stomates are confined to the lower surface; they are not frequent. The guard-cells are at the same level as the other epidermal cells, and their walls are only slightly thickened. The guard-cell ridges are small.

The chlorenchyma is differentiated. The palisade tissue consists of 2 layers of large typical palisade cells. The spongy parenchyma consists of smaller more or less irregular cells. All the mesophyll cells are thin-walled. There are air-spaces between the cells in both the spongy and the palisade tissue, but they are small. The cells contain numerous rather small chloroplasts, and many contain tannin. Oil-drops are found in some of the mesophyll cells and also in the cells of the upper epidermis.

The vascular bundles are small, and the parenchyma of both the xylem and the phloem contains tannin. Beneath each vascular bundle there is a small mass of stereome, consisting of small cells with very thick walls.

Stem (fig. 27).—The corky tissue forms a band of varying width; the cells are small, and have thick walls.

The cortex is a moderately wide band of very regular oval cells, which have thin walls and which contain tannin. This tissue has only very small intercellular air-spaces.

The phloem, xylem, and medullary rays are the same as in Dracophyllum Urvilleanum. The phloem parenchyma and the medullary rays contain tannin.

Scattered in the phloem and in the cortex there are more or less radial lines of small cells with suberized walls.

The pith is solid, and consists of large more or less polygonal cells with thickened lignified walls. These cells contain tannin.