Monographs Details: Dendroligotrichum
Authority: Smith, Gary L. 1971. Conspectus of the genera of Polytrichaceae. Mem. New York Bot. Gard. 21: 1-83.
Family:Polytrichaceae
Scientific Name:Dendroligotrichum
Discussion:

Fig. 21, 86-88.

Type: Polytrichum dendroides [Brid.] Hedw.

Catharinea sect Dendroligotrichum C. Müll. Syn. 1: 199. 1848.

Lectotype: Polytrichum dendroides [Bridel, Muse. Recent. 2(1): 101. t. 5. f. 6. 1798.] Hedwig, Sp. Muse. 102. 1801.

Polytrichum sect Lipotrichum Montagne in Gay, Hist. Fis. Poht. Chile Bot. 7: 70. 1850.

Type: Polytrichum dendroides [Brid.] Hedw.

Polytrichum subg Phalacroma Hooker f. & Wilson, Fl. Nov. Zel. 2: 96. 1854.

Holotype: Polytrichum dendroides [Brid.] Hedw.

Polytrichodendron Fleischer, Muse. Fl. Buitenzorg 1577. 1922. nom. nud.

Dendropogonatum Lorentz, in sched.

Dendroligotrichum is an austral genus with a distribution restricted to New Zealand and southern Chile. The genus is usually considered to include two species, D. dendroides (Hedw.) Broth., and the Fuegian D. squamosum (Hook. f. & Wilson) Card. In my opinion, the New Zealand plant would be better treated as a distinct taxon, Dendroligotrichum dendroides subsp microdendron (C. Müller) G. L. Smith, comb. nov. (Basionym: Catharinea microdendron C. Müller, Hedwigia 36: 339. 1897.). Dixon (1926) described the capsules of D. dendroides as "resembling those of Polytrichum alpinum, but this is true only of the N ew Zealand taxon; the South American plants have flaring, turbinate capsules. The condensed habit of subsp microdendron often resembles that of D. squamosum, leading Mitten to report that species from New Zealand, but the specimens so named in Mitten's herbarium (NY!) are not D. squamosum.. In addition to the difference in capsule shape, the leaves of subsp microdendron are shorter, much less finely attenuate, and have a more broadened sheath than in subsp dendroides.

Dendroligotrichum dendroides, "zwei Fuss hoch, ein Baumchen vorstellend, welche, in Menge beisammenstehend, sich jungen Anpflanzungen von Nadelholzwaldungen verahnlichen mogen" (Hampe, 1847), is undoubtedly the largest moss of the Americas, almost equalling the largest Dawsonia species. For most of its length, the slender, wiry stem is unbranched and either naked, or beset with scale-like leaves. Near the top, the shoot is abruptly ramified into numerous, fastigiate branches, each of which at maturity can produce a sporophyte, or a cup-like antheridial inflorescence, depending on the sex of the plant.

Stomata are uniformly distributed over the exothecium, and because of the pigmentation of the cells beneath each stoma, the capsule appears freckled with reddish spots (Fig. 21). The peristome arises from a high, fluted basal membrane, and is an intense, clear red. The calyptra is naked, or only sparsely hairy.

Dendroligotrichum seems related to Polytrichadelphus in the structure of its peristome (cf P. innovans), and in the dispersed pattern of stomatal distribution over the exothecium, but the aspect of the leaf cross-section, with its vertically elongated ventral cells, is more reminiscent of certain Pogonatum species [e.g., P. flexicaule Mitt., P. cirratum (Sw.) Brid.]. The intense pigmentation of the peristome is also a character associated with Pogonatum. The marginal cells of the leaf lamellae of D. squamosum are twinned; elsewhere in the Polytrichaceae, this type of lamellar modification occurs only in species of Pogonatum. On the other hand, the peristome of Dendroligotrichum has 64 teeth, as in Polytrichadelphus.

The distribution of the s])ecies of Dendroligotrichum (Fig. 94) indicates that it belongs to the group which I have called Antarctic radiants. Dendroligotrichum does not appear to have radiated into lower latitudes, as have Polytrichadelphus and Dairsonia, and in all likelihood its distribution has remained basically unchanged since the Pleistocene. When one considers how readily Dendroligotrichum could have been eliminated from either New Zealand or South America, he may wonder how many other taxa (e.g., Atrichopsis) which now occur only in one or the other area, may once have been more widelv distributed.