Remarks on X Leucoraoulia.
[Read before Wellington Philosophical Society, August 24, 1938; received by the Editor, September 14, 1938; issued separately, March, 1939.]
The delimitation of genera in the gnaphalioid composites is notoriously difficult, and New Zealand species have not escaped shuffling and reshuffling. It is now recognized that hybridism plays a part in the complex linkages. In an earlier paper (Allan, 1935, p. 224) remarks were offered on the leaf-characters of the “vegetable sheep” group of Raoulia. The polymorphy of R. eximia was pointed out, and the possibility that hybrids occurred between R. bryoides, R. eximia, and R. mammillaris. It was shown that R. bryoides belongs to the section “uninerves.” Here, I discuss hybrids noted between Leucogenes and Raoulia (subg. Psychrophyton), mainly observed during a survey made under grant from the Royal Society of London. For opportunities to study herbarium material, I am greatly indebted to Miss L. M. Cranwell (Auckland Memorial Museum), Miss E. M. Heine (Dominion Museum), Rev. Dr J. E. Holloway (Buchanan Herbarium), the Director, Royal Botanic Gardens, Kew (Kew Herbarium), the Keeper in Botany, British Museum of Natural History, Professor A. Wall, and Messrs F. G. Gibbs, R. M. Laing, W. Martin, G. Simpson, and J. Scott Thomson. My colleague, Mr V. D. Zotov, has assisted greatly by useful criticism and by providing the illustrations here used.
Earlier, Cockayne (1928, p. 284) had written of Raoulia rubra: “Apparently, this crosses with Leucogenes Leontopodium, one of the hybrids being the so-called species Raoulia Loganii (Buch.) Cheesem. Elsewhere, similar hybrids occur between Leucogenes grandiceps and Raoulia bryoides, one of which—described from individual only—is Helichrysum pauciflorum T. Kirk. Probably, Raoulia Gibsii Cheesem., Leucogenes Grahami Petrie, and a Stewart Island plant, originally referred by me to R. Loganii (in this case one parent would be R. Goyeni) are all edelweiss-vegetable sheep hybrids. H. H. Allan and I myself have found a number of other forms to which we attribute the same origin, and we have given to all such the provisional hybrid generic name × Leucoraoulia.” Cockayne and Allan (1934, p. 49) listed the groups: L. grandiceps × R. bryoides; L. grandiceps × R. Goyeni; L. Leontopodium × R. Grandiflora (doubtfully), and L. Leontopodium × R. rubra. They remarked, “Helichrysum Grahami Petrie is possibly L. grandiceps × H. selago.”
Raoulia was founded by Hooker (1853, p. 134) to include five species, and has been maintained by subsequent taxonomists. He remarks: “As a genus, it is not easily defined, except by its size and habit; it differs from Ozothamnus in the regular series of female florets; from Helichrysum by its habit, and very narrow receptacle; from Gnaphalium by the same characters.” Later Hooker (1864,
p. 147) included twelve species, dividing them into two groups, “It contains two natural and most distinct sections, of which one … has a convex, often hispid receptacle; achenes with very long silky hairs, a thickened areole at their base; and stout, rigid opaque pappushairs thickened at the tip; these, probably, constitute a good genus, to which the name Raoulia may be retained; the others may, perhaps, fall into Gnaphalium or Helichrysum.”
Beauverd (1910, p. 227) created the genus, Psychrophyton for the section with pappus hairs thickened above, and retained the residue in Raoulia. He is also (1910, p. 241) the creator of the genus Leucogenes to contain Helichrysum Leontopodium Hook. f. and Gnaphalium grandiceps Hook. f. Clear lines of differentiation between the three genera were drawn up. As between Leucogenes and Psychrophyton he remarks (1910, p. 218 and p. 242), “la principale differénce entre ces deux genres porte 1° sur la nature de l'akène è, qui est fertile chez les Leucogenes et stérile (toujours?) chez le Psychrophyton; 2° l'anatomie foliaire, qui est du type dimorphe chez les Leucogenes et du type homomorphe chez le Psychrophyton,” and “sauf en ce qui concerne la forme du stigmate et l'anatomie des feuilles florales, les affinités extérieures des Leucogenes sont avant tout pour le genre Psychrophyton.” The stigma differences are given as: Psychrophyton “sommet triangulaire ou lanceolé,” Leucogenes “sommet tronqué ou émarginé.”
Later, Beauverd (1912, p. 41) reduced Psychrophyton to a subgenus of Raoulia, principally because R. Petriensis was found to be “préeisement un type de transition d'autant plus indiscutable que du coté des Psychrophyton nouvellement examinés, nous avons observé chez certains organes (les stigmates tout spécialement) des formes exclusivement admises jusju'alors dans la constante générique adverse.” As Beauverd (1912, pp. 46, 48) states R. Petriensis has the numerous pappus hairs of Eu-raoulia, but these are in large part thickened upwards, while the achenes are pubescent. Even in species of Eu-raoulia clavately thickened hairs are occasional, and an examination of many specimens shows that Psychrophyton cannot be separated from Eu-raoulia as a clear-cut genus. R. Petriensis is a most distinct species; all the specimens I have seen agree in details, and there are no grounds for attributing its intermediate position to hybridism.
The two species of Leucogenes are, of course, easily recognised by the large, radiating floral leaves subtending the congested heads. The stigma differences are not so clear-cut, and the genus is, therefore, exceedingly close to those members of Raoulia coming into he subgenus Psychrophyton in the strict sense. The occurrence of hybrids is not, therefore, altogether surprising. As the bulk of the specimens seen by me are quite barren, I have illustrated leafcharacters.
1. Leucogenes grandiceps × R. bryoides. Figs. 1–3.
L. grandiceps occurs on the mountains of South Island throughout, and on Stewart Island. R. bryoides is confined to the drier
mountains of South Island. The two are found together in numerous localities. Forms of intermediate character are now known to be fairly frequent, but never occurring in quantity.
Kirk (1895, p. 351) based his Helichrysum pauciflorum (Fig. 2) on a specimen collected by L. Cockayne on the Craigieburn Mountains. He remarks on its “closest external appearance to H. grandiceps,” differing in the “solitary head” and the “total absence of the conspicuous woolly bracts.” Cheeseman (1925, p. 984) adds specimens of Cockayne from the Candlestick Mountains, and of Petrie from the Craigieburns. He notes that the “pappus hairs are those of the Psychrophyton section of Raoulia, with which it also agrees in the hispid achenes,” but does not place it in Raoulia on account of the “very different habit.”
Cheeseman (1910, p. 216) published his Raoulia Gibsii on specimens collected by Gibbs on Mount Starveall (Fig. 3) and Slaty Peak. He notes its very close resemblance to R. bryoides, but emphasizes its larger leaves and heads, and comparatively lax habit. The heads, as in H. pauciflorum, are sunk among the uppermost leaves, and contain more numerous florets than those of R. bryoides. He notes the observation of Mr. Gibbs that “at a little distance, it can easily be mistaken for a barren specimen of Helichrysum grandiceps.” There is very little, indeed, to separate the type specimens of H. pauciflorum and the Mount Starveall and other specimens. It will be seen that the leaves may be “uninerved” as in R. bryoides or “trinerved” as in L. grandiceps.
All the specimens here placed as hybrids are very similar in leaf-characters, though some may be dense cushions (as in the Mount Misery specimens) others (as in the Mount Starveall specimens) more open in habit. The conclusion that these aberrant plants are hybrids is strengthened by their sporadic occurrence and generally barren nature. Further material has been gathered on Mt. Fishtall (J. W. Hadfield), Mt. Schiza (J. W. Hadfield), Mt. Torlesse and the Craigieburn Mountains (H. H. A.) and Mt. Misery (H. H. A.). Similar forms have been collected on Mount Hutt (H. H. A.), where R. mammillaris rather than R. bryoides may be one parent. Mr. Gibbs has suggested to me that certain of his Mt. Starveall and Slaty Peak specimens may well be R. bryoides × grandiflora.
2. Leucogenes Leontopodium × Raoulia rubra. Figs. 4–8.
L. Leontopodium has a wide range in North and South Islands, and meets R. rubra on the Tararua Mountains. Buchanan (1882, p. 350) based his Haastia Loganii on specimens from Mt. Holdsworth. He describes the heads as 40–50 flowered, and the florets as “reddish.” His illustration shows a three-nerved leaf. Kirk (1899, p. 310) had only barren specimens, but pointed out that Buchanan's description and illustration of the achene, “compressed, linear, and covered with long, silky hairs,” fitted Helichrysum or Raoulia. Cheeseman (1925, p. 972), who had seen a number of specimens from the Tararua Mountains, gives the florets as 20–40, and remarks: “the pappus hairs are precisely those of the section Psychrophyton of
Raoulia, in which genus it must be placed.” I have seen a number of other specimens from the Tararua Mountains, but all in a barren state. All agree fairly well with one another, but some (Fig. 8) are much wider-leaved than others, and the leaves are occasionally uninerved. The intermediate nature of the leaves, the sporadic occurrences, and the general barrenness, all confirm the hybrid origin suggested. The reddish flowers also indicate the R. rubra parentage.
3.Leucogenes grandiceps × Raoulia Goyeni. Fig. 9.
Cockayne (1909, p. 64) doubtfully identified a specimen he collected on rocky ground near the summit of Mount Anglem, Stewart Island, as Helichrysum Loganii. Cheeseman (1925, p. 972) included it under R. Loganii, without any expression of doubt. No further specimens have been collected. Kirk (1884, p. 373) describes the leaves of R. Goyeni (confined to Stewart Island) as having “purple margins” and “close set whitish hairs.” In his fuller description (1899, p. 306) he does not refer to the purple colouration, and refers to the hairs as “short, white, uneven.” Beauverd (1912, p. 49) states “cils blanc-verdatre.” Cheeseman (1928, p. 971) gives the hair colour as “white.” In all the specimens seen by me (herbarium material only) the purple colouration is often quite marked, and the hairs of the summit leaves, seen in mass, are a dark brown. Seen individually, the hairs are paler to whitish. The specimens of the alleged R. Loganii are more open in habit than those of R. Goyeni, with looser hairs. These are tawny in mass, of a lighter shade than those of R. Goyeni, and the leaf margins occasionally show traces of purple. Leaves of both uninerved and trinerved type are to be found.
4.Leucogenes Leontopodium × Raoulia grandiflora. Figs. 10–12.
R. grandiflora extends all through and beyond the area occupied by L. Leontopodium.
Buchanan (1877, p. 529) based his Gnaphalium (Helichrysum) fasciculatum on specimens collected by Travers in the Tararua Mountains, and noted its similarity to R. grandiflora, except that it is “larger in all parts,” and has the flower-heads in “a sessile closely compacted fascicle.” Cheeseman (1912, p. 24) pointed out that the pappus-hairs are of the Psychrophyton-Leucogenes type. He reduces it to a variety of R. grandiflora. The figures (10–12) show the intermediate character of the leaves, and the congested flower-heads also indicate a L. Leontopodium parentage. No further flowering material has been noted, but specimens showing closely similar leaves and habit have been collected in several localities, growing in company with the parents. Certain of the specimens collected by Mr. Gibbs of Mount Patriarch (Fig. 12) and Slaty Peak, attributed to R. Gibbsii, belong here.
5.Helichrysum (Leucogenes) Grahami Petrie. Fig. 13.
This was described by Petrie (1913, p. 268) from a single collection made by Graham on the Sebastopol Ridge, Sealey Range. He speaks of the leaves as “everywhere densely clothed with loose greyish-white cottony tomentum, a few of the uppermost longer and broader, but not exceeding the heads.” These are “in capitate
fascicles.” In some respects it is intermediate between Helichrysum Vaill. and Leucogenes Beauverd. Cheeseman (1925, p. 980) places it doubtfully in Leucogenes, but remarks, “But the inflorescence, pappus-hairs, and achenes are so different from those of Leucogenes that I anticipate that it will ultimately fall into a different genus.” The resemblance of the leaves (Fig. 13) to those of the cross L. Leontopodium × R. grandiflora will be noted. Cockayne and Allan (1934, p. 49) suggested as a possible origin L. grandiceps × Helichrysum Selago. Certainly L. grandiceps appears very likely to be one parent, but until further search is made the matter must rest in doubt. I have collected a rather similar, quite sterile, plant on Mount Hutt, in company with L. grandiceps, H. Selago and R. mammillaris.
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