丝粉藻科 si fen zao ke
Guo Youhao (郭友好)[1]; Robert R. Haynes[2], C. Barre Hellquist[3]
Plants submerged in salt water. Rhizomes creeping, usually slender. Stems shortened. Leaves sessile, alternate, subopposite, or crowded at nodes, linear, with conspicuous midvein, sheathing at base. Plants dioecious. Flowers minute, unisexual, solitary or in cymes. Male flowers pedunculate; perianth of 3 small scales or absent; stamens 1–3; anthers connate, sessile, longitudinally dehiscent; pollen grains threadlike. Female flowers sessile; perianth absent or cupular or of 3 segments; carpels 2, free; style simple or divided into 2(–4) filiform stigmas; ovule 1, pendulous. Fruitlet achene- or nutlike. Seeds without endosperm.
Four genera with about 16–20 species; four species in China.
1a. Flowers in cymes; leaves subulate-terete ....................................................... 3. Syringodium
1b. Flowers solitary; leaves linear, flattened.
2a. Styles simple; anthers attached at different levels; leaves 1–4, alternate, 3-veined 2. Halodule
2b. Styles divided into 2 filiform stigmas; anthers attached at same height on stalk; leaves 2–7 together on short erect shoots, 7–17-veined ........................................................................... 1. Cymodocea
丝粉藻属 si fen zao shu
Rhizomes branched, rooting at nodes. Leaves 2–7 together on short erect shoots, flattened, linear, 7–17-veined; margin entire or dentate; sheaths auriculate, ligulate. Flowers solitary and terminal. Perianth absent. Male flowers pedunculate; anthers 2; pollen filiform. Female flowers sessile or subsesssile; styles divided into 2 filiform stigmas. Fruitlets laterally subcompressed, with bony pericarp, beaked.
About seven species: tropical to subtropical regions of the eastern hemisphere; only one species in China.
丝粉藻 si fen zao
Creeping rhizomes slender, each nodes with 1–3 roots and 1 short erect shoot. Leaves 2–5 together on shoots, ± falcate, 7–15 cm × ca. 4 mm, 9–15-veined, with secondary veins between lateral veins, sometimes slightly dentate toward apex, apex rounded to truncate; sheaths 1.4–4 cm. Anthers ca. 1.1 cm. Carpel ca. 5 mm along with slender styles. Fruitlet semicircular, ca. 1 cm, abaxially with 3 parallel ridges, middle ridge 6–8-toothed.
Marine, shallow sandy bottoms. Hainan (Sanya) [West Pacific Ocean, Indian Ocean to Red Sea].
[Ku suggests to add. 2. Cymodocea serrulata (R. Br.) Aschers. & Magnus 齿叶丝粉藻]
二药藻属 er yao zao shu
Diplanthera Thouars, Gen. Nov. Madag. 2, 3. 1806.
Rhizomes branched, rooting at nodes. Shoots erect, with 2 scales at base. Leaves 1–4, alternate, flattened, linear, 3-veined, margin toothed at apex; sheaths compressed, auriculate, ligulate. Flowers solitary and terminal, enclosed in a leaf. Male flowers consisting of 2 unequally inserted anthers, without filament; pollens filiform. Female flowers subsessile; style simple. Fruitlet laterally subcompressed, with bony pericarp, beaked.
About seven species: throughout most of the tropical regions; two species in China.
1b. Leaf tip truncate or obtuse, lateral teeth inconspicuous; leaves 0.5–0.8 mm wide; styles ca. 1.3 mm, lateral 2. H. pinifolia
二药藻 er yao zao
Zostera uninervis Forsskal, Fl. Aegypt. Arab. 120: 157. 1775; Diplanthera uninervis Forsskal.
Internodes of rhizome 2.5–3(–5) cm. Scales elliptic, membranous. Leaves narrowly linear, 4–11(–15) cm × 0.8–1.4 mm, veins 3, midvein conspicuous, gradually narrowed at base, lateral teeth conspicuous, trifid at apex; sheaths 2–3 cm. Flowers small. Peduncle of male flowers 1–2 cm; anthers ca. 0.5 mm. Style of female flowers 3–4 mm, apical. Fruitlet ovoid, ca. 2.5 × 2 mm; beak apical, ca. 1 mm.
Marine, shallow sandy bottoms. Hainan, Taiwan [??Indonesia, Japan including Ryukyus, Philippines, Thailand; Indian Ocean to Red Sea, W Pacific Ocean].
羽叶二药藻 yu ye er yao zao
Diplanthera pinifolia Miki, Bot. Mag. (Tokyo) 46: 787. 1932.
Internodes of rhizome 1–3 cm. Scales ovate, membranous. Leaves narrowly linear, 2–8 cm × 0.5–0.8 mm, veins 3, midvein conspicuous, lateral teeth inconspicuous, apex truncate or obtuse; sheaths 1–1.4(–2.8) cm. Flowers small. Peduncle of male flowers ca. 1 cm; anthers ca. 0.5 mm, sometimes with scales at base. Style of female flowers lateral, ca. 1.3 mm. Fruitlet ovoid, ca. 2 mm; beak lateral, ca. 1 mm.
Marine. Hainan, Taiwan [Indonesia, Japan including Ryukyus, Phillipines].
针叶藻属 zhen ye zao shu
Rhizomes branched, rooting at nodes. Shoots erect, with leaves 2 or 3, alternate, subulate-terete; sheaths broader, auriculate, ligulate. Plants dioecious; flowers in terminal cymes, enclosed in a leaf. Male flowers pedunclate, consisting of 2 equally inserted anthers, without filament; pollens filiform. Female flowers sessile; carpels free; style short, divided into 2 filiform stigmas. Fruitlet with bony pericarp, beaked.
Two species: one distributed in the Caribbean Sea and one in tropical areas from West Pacific Ocean to Indian Ocean; one species in China.
针叶藻 zhen ye zao
Cymodocea isoetifolium Ascherson, Sitzungsber. Ges. Naturf. Freunde Berlin 3. 1867.
Creeping rhizomes slender, each node with 1–3 roots. Scales ca. 5 mm. Leaves 7–10(–30) cm × 1–2 mm; sheaths 1.5–4 cm, ligule obtuse. Cymes 2.5–5 cm, enclosed in sheath of a reduced leaf. Peduncles of male flowers ca. 7 mm; anthers ovoid, ca. 4 mm. Ovary 3–4 mm; style ca. 2 mm; stigmas 4–8 mm. Fruitlet obliquely obovoid, ca. 4 mm; beak ca. 2 mm, apical.
Marine, shallow sandy bottoms. Guangdong (Naozhou Dao), Taiwan (Dongsha Dao) [tropical areas from Indian Ocean to W Pacific Ocean and its marginal seas].
[1] Herbarium or Wuhan University, Department of Biology, Wuchang, Hubei, People’s Republic of China
[2] Herbarium, Biological Sciences, Biodiversity and Systematics Department, University of Alabama, Box 870345, Tuscaloosa, Alabama 35487-0345, U.S.A.
[3] Department of Biology, Massachusetts College of Liberal Arts, North Adams, Massachusetts 01247-4100, U.S.A.