莎草蕨科 sha cao jue ke
Zhang Xian-Chun (张宪春)[1]; John T. Mickel[2]
Ferns, terrestrial. Fronds simple (linear) or fan-shaped, variously cleft and with dichotomous free veins; sporangia on margin, elaminate, branched or unbranched projections at lamina tips, not in discrete sori, exindusiate; spores bilateral, monolete, 128–256 per sporangium; gametophytes green and filamentous (Schizaea), or subterranean and non-green, tuberous (Actinostachys). Base chromosome numbers: x = 77, 94, 103.
Following the current understanding of fern phylogeny, two genera, Actinostachys and Schizaea, form a monophyletic family, with ca. 30 pantropical species; one genus Schizaea with two species in China.
莎草蕨属 sha cao jue shu
Plants evergreen, small. Rhizome siphonostelic, creeping or suberect, covered with septate hairs. Fronds linear and grasslike, or dichotomously branched and fanlike. Sporangia borne in 2–4 rows on extended fertile sporophores. Spores monolete. Gametophytes filamentous, algal-like.
More than 20 species: mainly in the tropics, two extending into S China.
1a. Fronds fan-shaped, several times dichotomously divided, with 5–10 fertile lobes at apex 1. S. dichotoma
1b. Fronds simple, linear, entire, except for 5–15 fertile lobes digitately placed at apex 2. S. digitata
分枝莎草蕨 fen zhi sha cao jue
Acrostichum dichotomum Linnaeus, Sp. Pl. 2: 1068. 1753; Schizaea biroi V. A. Richter; S. kikuzatonis M. Ogata.
Rhizome shortly creeping, bearing 1 or 2(–5) erect leaves; hairs on rhizome and stipe bases multicellular, brown to pale brown, ca. 3 mm. Fronds fan-shaped; undivided portion 20–50 cm; stipe not winged and barely distinct from winged portion or lamina, sparsely hairy; upper portion 2–8 × dichotomously divided, lamina-like with lobes 1–1.5 mm wide; whole lamina 10–30 × 7–20 cm, somewhat variable in size. Sporangium-bearing lobes 5–10 pairs arranged pinnately at apex of ultimate leaf lobes, lowest ones largest, 3–4 mm; sporangia in two regular rows on lobes, with long brown paraphyses.
Dry forest floors in lowlands. Hainan, Taiwan [India, S Japan, Myanmar, S Thailand; widely distributed in palaeotropics, Australia, New Zealand, and from Madagascar to Polynesia].
Plants from Taiwan and the Ryukyu Islands have been treated as a distinct species, but it is difficult to distinguish a local form of this widely distributed, variable species.
莎草蕨 sha cao jue
Acrostichum digitatum Linnaeus, Sp. Pl. 2: 1068. 1753; Actinostachys boninensis Nakai.
Rhizome shortly creeping, bearing several erect fronds; hairs on rhizome and stipes multicellular, brown, ca. 2 mm. Fronds crowded, linear, 20–30 cm tall, with indistinct stipes, simple and entire except for apical soriferous portion, 2–3.5 mm wide, with distinct midrib, entire, recurved when dry, basal 2–5 cm portion resembling stipe, triangular in cross section. Apex of vegetative portion of fronds constricted, bearing 5–15 soriferous lobes digitately. Soriferous lobes 2–4 cm × ca. 1 mm, entire; sporangia covering whole under surface of soriferous lobes, without paraphyses.
Forming small populations on rather dry forest floors in lowlands. Guangdong, Hainan, Taiwan, Yunnan [India, S Japan, Myanmar, Vietnam; widely distributed in palaeotropics from Madagascar to Polynesia].