Flora of New Zealand Series

Adelanthaceae (Jörg.) Grolle, J. Hattori Bot. Lab. 35: 327. 1972.

TribeAdelantheae Jörg., Bergens Mus. Skr. 16: 257. 1934.

Type: Adelanthus Mitt.

Plants strongly anisophyllous, firm to rather rigid, opaque or semiopaque, greenish, sometimes developing golden or brownish to fuscous (never reddish) pigments, medium to rather robust; leafy shoots ascending to erect and limited in height, usually unbranched except near base, arising from a system of creeping, rhizoidous, often interwoven, freely branched, leafless, whitish and colorless, plagiotropic and geotropic, stoloniform axes, the leafy shoots small-leaved below, often ± laterally compressed, often tapered and smaller-leaved distally, the shoot tips straight or often cernuous to circinate. Branching normally exclusively intercalary, ventral- or lateral-intercalary in origin, rarely (Calyptrocolea) with isolated Frullania -type branches, the branches usually from near bases of upright leafy shoots. Stems rigid, the cortex distinct, usually ± opaque, often with dark pigments, or (Wettsteinia) with a collapsing hyaloderm and firm-walled intracortical cells. Rhizoids at bases of erect leafy shoots but lacking above, common and scattered on leafless horizontal axes. Leaves often subvertically oriented, often asymmetric, the insertion subtransverse to succubous, extending to stem midline dorsally, the leaves unlobed and entire, at times bidentate or bearing numerous, small, ± regular teeth, the dorsal margin never deflexed, usually decurrent. Cells with walls firm and equally thickened or thinner and with strong trigones, in some species clearly elongated at the median base and forming a ± well-defined vitta; surface smooth. Oil-bodies finely granular to botryoidal. Underleaves lacking or mere slime papillae or vestigial. Asexual reproduction lacking or by 1–2-celled, smooth, greenish gemmae.

Dioecious. ♂ and ♀ Branches reduced, highly abbreviated, determinate, ventral-intercalary, basitonic, originating only from stoloniform axes or the leafless basal portion of erect leafy axes. Androecia minute, spicate, often vermiform, frequently coiled, determinate in length, often whitish and translucent; bracts minute, imbricate, distinctly ventricose; antheridia 1(2) per bract, the stalk uniseriate; bracteoles few-celled, vestigial, lacking antheridia. Gynoecial branches lacking vegetative leaves; bracts in (1)2(3) series, relatively small, unlobed or 2(3)-lobed, with apices or margins often toothed; bracteoles similar or somewhat smaller. Perianth (when developed) trigonous, inflated, the mouth wide, lobulate-ciliate; perianth often reduced or lacking and then with elaboration of a fleshy, green, polystratose, cylindric-clavate shoot-calyptra.

Foot conoidal, without but more often with an elaborated haustorial collar. Seta massive, with 50–85 rows of outer rows surrounding numerous, internal cells that are ± similar or a little larger. Capsule short- to moderately long-ellipsoidal, the wall fleshy, 4–8-stratose; outer layer of cells often with imperfect two-phase ontogeny or (Wettsteinia) with cells mostly devoid of thickenings.

Spores granulate or with papillae and very short-vermiculate markings or baculate. Elaters 2–3-spiral.

The Adelanthaceae, which occupy a very isolated position in the Cephaloziineae, are very largely Gondwanic in distribution and best developed in Australasia. The family consists of three genera; eight to nine are Neotropical-montane, two species occur in westernmost Europe, only one extends as far as Taiwan and no species occur in North America. All three genera occur in New Zealand. Most species of the family occur on soil or rocks, but a few (Pseudomarsupidium spp.) have become arboreal.

In Adelanthus and Wettsteinia all traces of a perianth have been lost and a fleshy shoot-calyptra is elaborated, bearing on its surface the unfertilized archegonia. A distinct perianth occurs only in Pseudomarsupidium. The species of Pseudomarsupidium are sometimes included in Adelanthus.

The generic name Adelanthus Mitt. (Mitten, 1864) is conserved against Adelanthus Endl., a flowering plant (see list of conserved names in Greuter et al., 2000), with A. falcatus (≡Jungermannia falcata Hook.) listed as the conserved type. Schuster (1967b, 1967c, 2002a) has argued that the type of Adelanthus Mitt. should be A. decipiens (Hook.) Mitt. He includes A. falcatus in his own genus Calyptrocolea R.M.Schust., the holotype of which is C. gemmipara R.M.Schust. (Schuster, 1967c). However, since the type of Adelanthus Mitt. is conserved, a change in the listed type can only be brought about by conservation. According to Art. 14.8 (McNeil et al., 2006), “The listed type of a conserved name may not be changed except by the procedure outlined in Art. 14.12,” i.e., by a formal proposal to the General Committee to be published in Taxon. To date, such a proposal has not been made. For further discussion, see Grolle (1972a, 2003).