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Volume 63, 1934
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– 544 –

Series III—Three-needle Pines (leaf section, sector).

P. canariensis. (Fig. 20.)

  • Comparative with: P. patula, with internal and median ducts.

    • P. Sabiniana, which has median ducts.

    • P. aristata, which has a characteristic non-plicate mesophyll.

  • Leaf section: Sector.

  • Epidermis: Even, regular, cubical cells with dot lumen.

  • Stomata: 3 + 3 on upper face, 4 to 6 on lower face. Guard cells sunk below hypodermis, outer passage urn-shaped.

  • Hypodermis: 2 or 3 rows of sclerosed cells, increased between stomata to groups of cells projecting into the mesophyll.

  • Mesophyll: 2 rows of plicate, hexagonal cells, the outer row deeply infolded.

  • Resin ducts: 2 marginal; of about 9 sclerosed cells surrounding an epithelial layer.

  • Endodermis: Circular, large, unthickened cells.

  • Vascular strand: Roughly triangular; V-B 2, large, an are of thickened parenchyma subtending the bundles, a few “rays” traversing xylem and phloem.

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Fig. 20

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P. caribaea. (Figs. 21, 22.)

  • Comparative with: P. Banksiana, which has a sclerosed layer and stomata in lines of 6 and 9.

  • Leaf section: Semi-circular or a sector.

  • Epidermis: Regular, square, much thickened, with dot lumen.

  • Stomata: 5 + 5 on each upper face, 12 on lower. Guard cells sunk below hypodermis.

  • Hypodermis: A row of regular thin-walled cells or water layer, in places strengthened by sclerenchyma cells.

  • Mesophyll: 2 rows of deeply plicate 5 lobed cells.

  • Resin ducts: 4 internal; of 1 row of 8 cells thickened, but not sclerosed. Sometimes 2 median ducts.

  • Endodermis: Irregular, almost spherical, cells with outer wall thickened.

  • Vascular strand: Elongated elliptical; vascular bundles 2; with transfusion tissue on the flanks, surrounded by large-celled parenchyma; “rays” visible.

N.B.—In leaves of 3-needle bundles, the two vascular bundles are almost in contact.

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Fig. 21

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Fig. 22

– 546 –

P. Coulteri (Rotorua). (Fig. 23.)

  • Comparative with: P. rigida and P. palustris. This species is distinguished by the greater size of its leaf section and the large proportion of sclerosed hypoderm cells.

  • Leaf section: Sector.

  • Epidermis: Regular, square, thickened cells, with dot lumen.

  • Stomata: 12 + 5 + 5, on all faces; guard cells sunk below epidermal layer, thickened on both walls.

  • Hypodermis: In groups of 3–4 rows thick projecting into the mesophyll between the stomata; of sclerosed cells, increased at angles.

  • Mesophyll: Plicate, 6 lobed cells.

  • Resin ducts: 2 or 4 median, placed at angles and in centre of the lower face; of 1 row of thickened small cells, lined by several broken rows of epithelia.

  • Endodermis: Regular, elliptical cells with thickened outer and lateral walls.

  • Vascular strand: Elliptical, extensive, 2–3 vascular bundles, surrounded by thin-walled parenchyma, and subtended on the upper face by a T-shaped mass of thickened sclerenchyma tissue.

N.B.—In South Island specimens, endodermis has lateral walls only thickened, and V.B. is triple-branched.

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Fig. 23

– 547 –

P. leiophylla (Rotorua). (Fig. 24.)

  • Comparative with: P. Montezumae, which has a distinct schleroderm layer in the hypodermis.

    • P. excelsa and P. strobus, which have peripheral ducts.

    • P. Armandi, which has stomata on 2 faces only.

    • Leaf section: Triangular.

  • Epidermis: Flattened, ovate cells, with much thickened walls.

  • Stomata: 4 + 4 on upper face, 4 on lower. Guard cells slightly sunken, large, thickened on both faces.

  • Hypodermis: 1 row of unthickened cells, increased at angles and occasionally by several thick-walled cells.

  • Mesophyll: 2 rows of slightly plicate cells, with palisade infolding on all faces.

  • Resin ducts: 2 median; of 2 rows of large unthickened cells surrounding a small cavity.

  • Endodermis: Elliptical cells larger than and distinct from the inside parenchyma, thickened on outer walls.

  • Vascular strand: Circular; 2 V-B surrounded by thin-walled parenchyma, a line of thickened cells joining the bundles; some albuminous cells against the phloem.

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Fig. 24

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P. palustris (Rotorua). (Fig. 25.)

  • Comparative with: P. caribaea, which has occasional median ducts and a distinct water layer, with no sclerenchyma.

  • P. tuberculata, with additional median ducts, and which differs also in having a water layer.

  • Leaf section: A sector.

  • Epidermis: Even, cubical cells with dot lumen.

  • Stomata: 3 + 4 on upper face, 10 on lower. Pores not sunk, guard cells sunk to the level of hypoderm.

  • Hypodermis: 2 rows irregularly increased to 3 rows of sclerosed cells.

  • Mesophyll: 2 rows of slightly plicate 4 lobed cells without a palisade formation.

  • Resin ducts: 2 internal; of an outer row of 12 somewhat thickened cells with an inner row of 9 similar cells, cavity small.

  • Endodermis: Regular, distinct, elliptical cells, thickened on lateral walls.

  • Vascular strand: Elliptical, 2 vascular bundles, spreading; a little transfusion tissue present; “rays” visible in xylem. The tissue opposite the protoxylem appears spongy, and constantly breaks apart, leaving large air spaces.

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Fig. 25

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P. patula. (Fig. 26.)

  • Comparative with: P. canariensis, which has marginal ducts.

  • Leaf section: A sector.

  • Epidermis: Much thickened elliptical cells.

  • Stomata: 3 + 3 on upper face, 6 on lower face.

  • Hypodermis: 1 layer of water cells and an inner, slightly thicker walled, but unsclerosed layer.

  • Mesophyll: 2 rows of plicate, 4 lobed cells, with palisade infoldings.

  • Resin ducts: 2 median and 2 internal, the former of about 10 cells round a large cavity, the internal ducts smaller.

  • Endodermis: Large, almost spherical cells, thickened on the outer and lateral walls.

  • Vascular strand: Slightly elliptical; V-B 2, surrounded by thin-walled parenchyma, with a mass of albuminous cells opposite the phloem, “rays” traversing the phloem.

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Fig. 26

– 550 –

P. ponderosa (Botanical Gardens, Wellington). (Fig. 27.)

  • This species closely resembles P. Jeffreyi, but in the latter there is no distinct water layer, and only 1 or 2 rows of sclerosed cells.

    • It differs from P. scopulorum in having no water layer in the hypodermis.

    • No definite character distinguishes this section from that of P. rigida.

  • Section: Sector.

  • Epidermis: Regular, cubical cells with dot lumen and distinctly thickened cuticle.

  • Stomata: 3 + 3 on upper face, 8 on lower face. Guard cells deeply sunk to lowest layer of hypodermis; entrance tube bounded by crescent-shaped epidermal cells, and opening at the outer level of the epidermal layer.

  • Hypodermis: 4–5 rows of irregularly shaped sclerenchyma cells.

  • Mesophyll: 3 rows of plicate, hexagonal cells.

  • Resin canals: 3 median placed at the angles; about 25 sclerosed cells in a double row around the epithelial layer.

  • Endodermis: Regular, elliptical, thickened on outer and lateral walls.

  • Vascular strand: Elliptical, large; vascular bundles 2, connected on their lower sides by a narrow band of thickened cells, while a band of sclerosed cells borders the thin-walled parenchyma adjoining the xylem. A mass of “albuminous” tissue flanks the bundles and adjoins the outer transfusion tissue. Several “rays” are visible traversing xylem and phloem.

N.B.—The macroscopical characters of this tree were similar to type P. Jeffreyi.

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Fig. 27

– 551 –

P. Jeffreyi (Rotorua). (Fig. 28.)

  • Comparative with: P. ponderosa and P. scopulorum, the former differs in having 3 to 5 rows of sclerosed hypodermal layer and the latter differs in its distinct water layer.

    • P. Sabiniana, which has no water layer but 2–3 rows of sclerosed hypodermis.

  • Leaf section: Sector.

  • Epidermis: Regular, cubical cells, cuticle thick, outline widely crenated.

  • Stomata: 5 + 6 on upper faces, 8 on lower. Guard cells sunken, thickened on both faces.

  • Hypodermis: 2 rows of thickened but not sclerosed cells, the outer row on the upper faces, with thinner walls.

  • Mesophyll: 2 to 3 rows of plicate, 5 or 6 lobed cells.

  • Resin ducts: 3 median; of about 12 outer thickened cells, with a disintegrating epithelial lining.

  • Endodermis: Elliptical cells, thickened on outer wall.

  • Vascular strand: Flattened, elliptical V-B 2, spreading; a mass of sclerenchyma fronts the lower face of the bundles, which are joined by a line of thickened tissue on the upper face; much transfusion tissue adjoins the vascular tissue.

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Fig. 28

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P. scopulorum (Rotorua). (Fig. 29.)

  • Comparative with: P. ponderosa and P. Jeffreyi, from which it differs in its distinct water layer.

    • P. Sabiniana, which has no water layer.

    • P. rigida, with small resin ducts.

  • Leaf section: A sector.

  • Epidermis: Regular, cubical cells.

  • Stomata: 5 + 5 on upper faces, 8 on lower face. The cells bounding the pore are slightly sunk below the surface, and cause a wide crenation of the leaf outline. Guard cells sunk to level of hypodermis.

  • Hypodermis: 1 distinct water layer and 2 rows of sclerenchyma, increased to 3 or 4 in the groups of the lower face.

  • Mesophyll: 3 rows of plicate cells with palisade infoldings.

  • Resin ducts: 3 or 4 median; of 1 row of 13–15 thickened cells.

  • Endodermis: Large, almost circular cells, thickened on the outer wall.

  • Vascular strand: Elliptical, with 2 vascular bundles surrounded by thin-walled parenchyma, except for an arc of thickened cells subtending the xylem; some transfusion tissue flanks the bundles.

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Fig. 29

– 553 –

P. radiata (Fig. 30.)

  • Comparative with: P. halepensis, which has 6 peripheral resin ducts and 1 row of sclerosed hypodermis.

  • Leaf section: A sector, occasionally semi-circular, margin crenate, interrupted by stomata.

  • Epidermis: Regular, uniform, square cells with thickened walls and dot lumen.

  • Stomata: 4–6 on each upper face, 7–10 on lower face. Deeply sunken, of characteristic shape, with the outer bordering pair of epidermal cells each prolonged into a sharp beak enclosing an outer stomatal space; the inner guard cells thickened on both outer and inner walls, and the inner air space bounded by a U-cell of mesophyll tissue.

  • Hypodermis: 1 layer of thin-walled pseudo-water layer cells together with 2 rows of regular sclerosed cells.

  • Mesophyll: A palisade layer with 2 or 3 inner rows of plicate cells.

  • Resin ducts: Usually 2 median, but frequently lacking; duct consists of 1 row of 10 cells with unthickened walls and an inner row of secreting cells.

  • Endodermis: Regular large elliptical cells thickened on outer and lateral walls.

  • Vascular strand: Large, elliptical; 2 vascular bundles, surrounded, except on the polar extremities, by thickened parenchyma; between this layer and the endodermis is thin-walled large-celled parenchyma; several “rays” visible in xylem and phloem.

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Fig. 30

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P. rigida. (Fig. 31.)

  • Comparative with: P. ponderosa and P. Jeffreyi, which have no water layer, and with P. scopulorum, which has similar structure but a smaller vascular strand.

  • Leaf section: Sector.

  • Epidermis: Cubical, regular cells.

  • Stomata: 7 + 7 on upper faces, 9 on lower. Openings not sunk, guard cells slightly sunk, thickened on both faces, inner pore bounded by U-cell.

  • Hypodermis: 3 rows of sclerosed cells, the outer row of small, thinner-walled cells, but not a distinct water layer.

  • Mesophyll: 2 rows of 5–7 lobed plicate cells, the outer walls with palisade infoldings.

  • Resin ducts: 2 or 3 median; small, of 9 thickened cells with inner epithelial layer.

  • Endodermis: Regular, distinct, many elliptical cells, thickened on outer and lateral walls.

  • Vascular strand: Elliptical, large, lined with regular thin-walled parenchyma; vascular bundles 2, spreading; xylem regular, with transfusion tissue on flanks, phloem flanked by distinct masses of albuminous cells; no “rays” visible.

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Fig. 31

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P. Sabiniana. (Fig. 32.)

  • Comparative with: P. canariensis, with peripheral resin ducts.

    • P. yunnanensis, with over 5 resin ducts, peripheral.

    • P. patula, with sometimes internal ducts, and a much smaller leaf section.

    • P. palustris, with internal resin ducts.

  • Leaf section: Sector.

  • Epidermis: Outline widely crenate; of regular, square, much thickened cells.

  • Stomata: 4 + 4 on upper faces, 7 on lower face. Guard cells slightly sunk, thickened on inner and part of outer wall.

  • Hypodermis: 2–3 layers of hexagonal, sclerosed cells.

  • Mesophyll: Large, slightly plicate.

  • Resin ducts: 2, median, placed at angles; of 2 or more rows of thickened cells surrounding an epithelial layer.

  • Endodermis: Regular, elliptical cells with laterally thickened walls.

  • Vascular strand: Reniform; 2 V-B connected by thin-walled parenchyma; an are of thickened cells adjoins the phloem.

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Fig. 32

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P. taeda (Rotorua). (Fig. 33.)

  • Comparative with: P. leiophylla and P. Lambertianu, which have no sclerosed hypodermal layer.

    • P. radiata, which is larger, with characteristic stomata and only a pseudo-water layer.

  • Leaf section: A sector.

  • Epidermis: Regular, much thickened cells.

  • Stomata: 4–9 + 4–9 on upper faces, 9–15 on lower face. Slightly sunk; guard cells thickened on both walls.

  • Hypodermis: 1 row of water layer cells and 1 of irregular sclerosed cells, increased at angles.

  • Mesophyll: Slightly plicate, circular cells, slight palisade infoldings.

  • Resin ducts: 2 median; outer layer of 12 slightly thickened cells with epithelial lining.

  • Endodermis: Regular, large celled; with outer and laterally thickened walls.

  • Vascular strand: Cordate; vascular bundles 2, placed close together; parenchyma thin-walled, bundles by transfusion tissue; distinct “rays” present.

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Fig. 33

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P. tuberculata (Rotorua). (Fig. 34.)

  • Comparative with: P. radiata, which differs in having extra resin ducts peripheral and fewer stomata.

    • P. palustris, with no water layer.

    • P. canariensis, without a water layer.

    • P. caribaea, with no scherenchyma layer.

    • P. yunnanensis, which differs in having many (6), marginal ducts, an ill-defined water layer, and only 1 row of sclerosed hypoderm.

  • Leaf section: Sector.

  • Epidermis: Regular, cubical, much thickened cells.

  • Stomata: 5 + 5 on upper face, 8 on lower face. Guard cells sunk, partly thickened on both faces; the bounding epidermal cells large at the base.

  • Hypodermis: A distinct water layer, bounded on the inner side by 1, increased occasionally to 2, rows of sclerenchyma.

  • Mesophyll: 2 rows of deeply plicate, 8 lobed cells; marked palisade infoldings.

  • Resin ducts: 2 median and 2 internal; of an outer row of about 10 unthickened cells and an inner row of 5–6; the ducts are often all median.

  • Endodermis: Large, elliptical, scarcely thickened cells, but thickened on lateral walls with a distinct endodermal dot.

  • Vascular strand: Elliptical; vascular bundles 2, closely placed, and surrounded by much unthickened parenchyma; a mass of transfusion tissue on either flank of the bundles; no “rays” present.

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Fig. 34

– 558 –

P. yunnanensis. (Fig. 35.)

  • Comparative with: P. tuberculata, with median and internal ducts.

    • P. radiata, which has only median ducts and several hypodermal layers.

    • P. canariensis, with schlerenchyma in groups, stomata in threes.

  • Leaf section: A sector.

  • Epidermis: Regular, oblong cells giving an even, unbroken outline.

  • Stomata: 3 + 3 on upper face, 11 or 12 on lower face. Guard cells slightly sunk, thickened on both faces.

  • Hypodermis: 1 layer of small-sized pseudo water cells and an inner row of larger, slightly thickened cells, slightly increased at angles.

  • Mesophyll: 2 rows of many lobed plicated cells.

  • Resin ducts: 6 peripheral, of which 4 are placed on the lower face and 2 median opposite the angles; composed of 7–9 outer cells, slightly thickened, and an inner layer of thin-walled cells around a small cavity.

  • Endodermis: Regular, elliptical cells, thickened on outer and lateral walls.

  • Vascular strand: Elliptical, V-B 2, spreading; a mass of thickened cells with cell contents lies on the upper part of the stele, subtending the arc of vascular tissue; xylem is divided into groups by the rays which traverse it and the phloem.

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Fig. 35