Tropicos | Name - Helodiaceae Ochyra

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Helodiaceae Ochyra

Project Name Data (Last Modified On 2/20/2009)

Acceptance : Accepted

Project Data (Last Modified On 3/30/2009)

General Reference:

Hu, R.-L., Y.-F. Wang, M. R. Crosby & S. He. 2008. Amblystegiaceae—Plagiotheciaceae. 7: viii + 258 pp. In Moss Fl. China. Science Press & Missouri Botanical Garden, Beijing, New York & St. Louis.

Notes (Last Modified On 3/30/2009)

general taxon notes:

Species of the Helodiaceae differ from those of the Thuidiaceae by the shape of paraphyllia (Ochyra 1989). In the Helodiaceae, the paraphyllia are smooth, never papillose, acute, and composed of elongate cells mostly with oblique walls; while in the Thuidiaceae, the paraphyllia are always short-celled, strongly papillose, and ending in truncate cell walls with two papillae. According to Ochyra (1989), three different types of paraphyllia are found in the Helodiaceae: 1) the lanceolate type in Palustriella Ochyra, having unbranched structures consisting of two to many rows of cells in the basal portion and uniseriate in the apical portion; 2) the lanceolate-ciliate type in Actinothuidium (Besch.) Broth. and Bryochenea C. Gao & G.-C. Zhang, having mostly narrowly lanceolate paraphyllia with numerous acute, uniseriate cilia at margins; and 3) the filiform-branched type in Helodium Warnst., having paraphyllia consisting of a single row of elongate cells.

Touw (2001b) accepted Actinothuidium, Bryochenea, and Helodium in the Thuidiaceae, but did not include Palustriella, which was described by Ochyra (1989) to accommodate Cratoneuron commutatum (Hedw.) G. Roth. This species was excluded from the Amblystegiaceae in the Chinese flora (R.-L. Hu & Y.-F. Wang 20005), but was left untreated. It is here treated in the Helodiaceae. The family was described by Ochyra (1989), and it has been recognized by several recent authors (Buck & Goffinet 2000; Crosby et al. 2000; Goffinet & Buck 2004). A synopsis of the Helodiaceae is presented here, including Actinothuidium, Bryochenea, Helodium, and Palustriella.

The species from the above-mentioned four genera have been treated in China in the Amblystegiaceae or Thuidiaceae (P.-C. Chen et al. 1978; P.-C. Wu et al. 2002). There are some degrees of taxonomic ambiguity regarding the placement and classification of several species that are discussed below. It is clear that there is a need to recognize the Helodiaceae in order to include some previously untreated species. The synopsis of the Helodiaceae given below reflects the updated information about the recent classification of mosses (Goffinet & Buck 2004).

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HELODIACEAE

沼羽藓科 zhao yu xian ke

by Si He

Plants stout to rather robust, sometimes delicate to medium-sized, dark green, yellowish green, or brownish, not glossy, or somewhat glossy, in tufts or large cushions or interwoven mats. Stems erect, ascending, or more or less prostrate, often regularly pinnately branched; central strand absent or weakly differentiated; paraphyllia multi-branched, densely spread on stems and branches, filiform-branched, lanceolate-ciliate, or lanceolate, smooth, not papillose, composed of elongate cells with oblique cell walls, ending in an acute cell; rhizoids reddish brown at lower portion of stems. Stem and branch leaves similar or polymorphic; stem leaves appressed or incurved when dry, erect-patent when moist, gradually narrowed from cordate, ovate, or triangular base to a lanceolate apex, often secund toward one side, usually longitudinally plicate; margins slightly revolute, serrate or dentate above; costae single, thick, to ca. 4/5 the leaf length; median leaf cells pellucid, oblong-rhomboidal or oblong-hexagonal, slightly prorate, thin-walled, or finely unipapillose; apical cells oblong, smooth; basal cells rectangular; branch leaves ovate-lanceolate, often abruptly narrowed toward apex. Autoicous or dioicous. Inner perichaetial leaves erect, oblong-lanceolate, often serrate, deeply plicate, costae ending below the apex. Setae elongate, 20–50 mm long, smooth; capsules inclined to horizontal, oblong-ovoid or cylindrical, slightly curved to strongly curved; opercula conic, shortly to long-rostrate; annuli usually differentiated; peristome double; exostome teeth narrowly lanceolate; endostome segments nearly as long as teeth, perforate; basal membrane rather high; cilia absent or weakly to rather well developed, nodulose. Calyptrae cucullate, smooth. Spores spherical, finely papillose.