Home Central American Mosses
Home
Name Search
Family List
Generic List
Species List
!Helicophyllum Brid. Search in The Plant ListSearch in Index Nominum Genericorum (ING)Search in NYBG Virtual HerbariumSearch in JSTOR Plant ScienceSearch in SEINetSearch in African Plants Database at Geneva Botanical Garden Decrease font Increase font Restore font
 

Published In: Bryologia Universa 2: 771. 1827. (Bryol. Univ.) Name publication detail
 

Project Name Data (Last Modified On 2/24/2011)
Acceptance : Accepted
Project data     (Last Modified On 2/24/2011)
Discussion:

Helicophyllum is a monotypic genus and the sole member of the Helicophyllaceae. It has creeping stems with lateral leaves that are strongly inrolled when dry. Its stems are densely tomentose on the ventral surface, but the rhizoids, which are highly branched, come from relatively few rhizoidal initials found mainly along the line of the leaf insertion. It has dimorphic leaves, but unlike those of Racopilum in which the dorsal and lateral leaves are different, in Helicophyllum the ventral and lateral/dorsal leaves differ. The lateral leaves in Helicophyllum resemble those of some Macromitrium species in overall form and in having stoutly unipapillose to mammillose leaf cells. The genus has a number of odd sporophytic features that  isolate it from most other mosses. Its capsules are immersed, eperistomate, stomata are absent, and its operculum is flat and inserted within the capsule mouth which is thickened and distinctly inrolled. Buck and Vitt (1986) attribute a hairy calyptra to Helicophyllum, but I have not observed this. In fact, a calyptra appears to be absent in Helicophyllum as judged from the fact that even young capsules, completely enclosed by perichaetial leaves, lack a calyptra. Helicophyllum has terminal perichaetia and perigonia, with perigonia also occurring at the ends of short lateral branches. Paraphyses are present in the perigonia of Helicophyllum, but absent from the perichaetia.


 

Export To PDF Export To Word

Helicophyllum Brid., Bryol. Univ. 2: 771. 1827.

Medium-sized plants in mats. Stems creeping, irregularly branched, central strand present, densely reddish‑brown tomentose on underside of stem; rhizoidal initials clustered below leaf insertions and scattered along the stem; axillary hairs 2–3‑celled, basal 1–2 cells short, quadrate, brownish‑red, apical cell enlarged, oval to oblong, thin‑walled, hyaline. Leaves dimorphic: lateral leaves wide‑spreading when wet, often complanate in 2 rows, inrolled contorted when dry, lingulate to oblong‑ovate; apices broadly rounded to obtuse; margins narrowly recurved, bordered by smooth, linear cells, entire; costae single, ending near the apex; upper cells quadrate to rounded‑hexagonal, thin‑walled, bulging mammillose, or stoutly unipapillose, dorsal leaves oblong to ovate, half the size of lateral leaves, otherwise similar; ventral leaves small, nearly buried in tomentum, lanceolate to triangular‑acuminate; upper leaf cells short‑rectangular, thin‑walled, pellucid, unipapillose. Dioicous. Perigonial buds swollen, terminal on stem or on short lateral branches; leaves ovate; costae percurrent to short excurrent; cells elongate below, short‑rectangular above, smooth or weakly papillose; paraphyses present. Perichaetia at ends of stems or branches, greatly enlarged and differentiated; leaves oblong‑lanceolate; acuminate; margins revolute to near apex, serrulate above; costae shortly excurrent; cells elongate, smooth; paraphyses absent. Setae very short to apparently absent. Capsules immersed, erect, symmetric, abruptly incurved at mouth, cupulate to oblong, smooth when dry, irregularly dehiscent; stomata absent; opercula flat to slightly convex, at times shortly apiculate, irregular at margins, inserted within the capsule mouth; peristome absent. Spores papillose. Calyptra absent (?).

 
 
© 2015 Missouri Botanical Garden - 4344 Shaw Boulevard - Saint Louis, Missouri 63110