Flora of New Zealand Series

Thallus fruticose, dendroid, sometimes ± dorsiventral with rudimentary cyphellae on lower surface, robust to rather delicate, arising from a ± terete, root-like holdfast, corticolous, rarely saxicolous, 1-5(-10) cm tall. Branches terete to flattened, complex, entangled, ± corralloid at apices, subdichotomously divided below from 1-4 prominent, primary stems. Surface glabrous to ± uniformly pubescent or tomentose, pubescence slight, short, to thick and woolly, pale buff or yellow-brown, coralloid branchlets at apices grey, grey-brown or brown-black often with a reddish tinge, often prominently maculate or mottled (×10 lens). Medulla white. Photobiont blue-green, Nostoc or Scytonema, radially arranged below upper cortex in primary branches, ± homoiomerous towards apices of secondary coralloid branchlets. Apothecia unknown.

Although Dendriscocaulon was included in Polychidium in the family Peltigeraceae [Henssen Symb. bot. upsal. 18: 99 (1963)], evidence [Wilson Proc. Roy. Soc. Q'land 7: 8-11 (1891); Dughi Annls Fac. Sci. Marseille 16: 147-157 (1944); James and Henssen, in Brown et al. (eds) "Lichenology: Progress and Problems", pp. 27-77 (1976)] strongly suggests that the mycobiont in Dendriscocaulon be accommodated in the family Lobariaceae. At least two species occur in New Zealand as independent individuals and related species are found as cephalodia-like outgrowths on thalli of Sticta filix, S. latifrons, and S. subcaperata, all of which have green algae as primary photobiont. Dendriscocaulon grows in damp, humid, strongly shaded habitats and for this reason is often overlooked. Species are mainly corticolous, often among mats of bryophytes and other lichens and in some Fiordland habitats are found on spray-drenched rocks near streams and waterfalls. The New Zealand species, both free-living and in association with a green alga in caulescent species of Sticta are different from the European D. umhausense (Auersw.) Degelius, formerly known as D. bolacinum (Ach.) Nyl., which is associated with Lobaria amplissima.

Dendriscocaulon is still very poorly and inadequately collected in New Zealand and urgently needs further study in both free and combined states. Useful information on the genus is given by Dughi [ Bull. Soc. bot. fr. 83: 671-693 (1936); Bull. Soc. bot. fr. 84: 430-437 (1937); Annls Fac. Sci. Marseille 16: 147-157 (1944); Annls Fac. Sci. Marseille 16: 239-242 (1945)], and James and Henssen (loc. cit.) .