槐叶苹科 huai ye ping ke
Two genera and ca. 17 species: tropical to temperate regions worldwide; two genera and three species in China.
Lin Youxing. 2000. Salviniaceae and Azollaceae. In: Lin Youxing, ed., Fl. Reipubl. Popularis Sin. 6(2): 340–345.
槐叶苹属 huai ye ping shu
Lin Youxing (林尤兴), Shi Lei (石雷); A. Michele Funston
Ferns, floating, small. Stems horizontal, slender, covered with hairs and protostele. Fronds 3, verticillate, sessile or very shortly stipitate; two fronds floating on water surface, normally elongate, green, entire, hairy, and densely covered with papillae on upper surface, costae slightly distinct; other frond submersed and finally dissected and rootlike. Sori clustered at stipe bases of submersed fronds, or double attached along submersed ones; microsporocarp large and containing majority of microsporangia, each microsporangium containing 64 microspores; megasporangia vase-shaped, each one only containing 1 megaspore, trilete, experispore, with small retuse on exine; microspores sphaeropteroid, trilete mark finer, exine of mark usually retuse, triangular, experispore, exine thinner, smooth. x = 9.
About ten species: worldwide, mostly in American and African tropics; one species in China.
槐叶苹 huai ye ping
Marsilea natans Linnaeus, Sp. Pl. 2: 1099. 1753.
Stems covered with dark brown articulate hairs. Fronds 3, verticillate; two fronds normal, floating, Robinia-shaped, 0.8–1.4 × 0.5–0.8 cm, base rounded or subcordate, entire, apex obtuse; stipe ca. 1 mm or fronds sessile. Venation obliquely spreading, veinlets 15–20 pairs on either side of costa, each one with 5–8 bunches of white setae. Fronds herbaceous, deep green adaxially, densely brown villous abaxially; submersed fronds finally dissected into linear segments, covered with hairs, rootlike and acting as roots. Sporocarps 4–8, clustered at bases of submersed fronds, with sparse bunches of hairs; microsporocarps yellowish, megasporocarps brownish.
Floating on rice fields, ponds, ditches, widely distributed in valleys and regions of Chang Jiang. N and NE China, Taiwan, Xinjiang [India, Thailand, Vietnam; Africa, Asia, Europe].
The whole plant is used medicinally; it is boiled and eaten for consumptive disease and eczema and externally used for inflammatory diseases affecting the skin.
The name Salvinia natans has been misapplied to plants in North America (S. minima Baker).
满江红属 man jiang hong shu
A. Michele Funston
Carpanthus Rafinesque; Rhizosperma Meyen.
Ferns, usually small, floating. Stems prostrate or erect, very short and slender, easily broken, green, with protostele, pinnately branching or falsely dichotomously branching, normally decumbent and floating on surface of water, or lotuslike when growing in shallow water or in crowded situations up to 3–5 cm high above water surface. Fronds sessile, alternate, in 2 rows along upper side of stem, often imbricate, partite into dorsal (upper emersed) lobe and ventral (lower immersed) lobe; dorsal lobe floating on water surface, oblong or ovate, slightly concave abaxially at middle, densely papillose adaxially, green, fleshy, with a cavity near base containing blue-green algae (Anabaena); ventral lobe shell-like, membranous, tightly imbricate, transparent, colorless, or reddish and slightly incrassate near base; sometimes ventral lobe changing into and acting same as dorsal lobe when plant in erect growing state; lamina changing from green to yellow or red depending on environmental conditions (e.g., high temperature, lack of nutrients, salinity). Sporocarp usually in pairs, rarely 4-clustered, at base of lateral branches; megasporocarp located under microsporocarp, oblong or ovoid, containing 1 megasporangium producing 1 functional megaspore; megaspore topped with conic structure (indusium) covering 3–9 colorless spongelike floats and an Anabaena colony; microsporocarps globose or peachlike, large, 4–6 × size of megasporocarp, umbonate at apex, exine thin and transparent, containing majority of microsporangia, each microsporangium containing 32 or 64 microspores, embedded in 5–8 colorless massulae, covered with different attachments according to different species. x = 22.
About seven species: tropical to temperate regions worldwide; two species in China.
1a. Megasporangia with 9 floats on exine, massulae with few simple or irregularly branched silklike hairs; lateral branches distinctly axillary and numbers same as frond numbers ...................... 1. A. imbricata
1b. Megasporangia with 3 floats on exine, massulae with several anchorlike hairs; lateral branches axillary and numbers less than frond numbers .................................................................. 2. A. filiculoides
满江红 man jiang hong
Salvinia imbricata Roxburgh, Calcutta J. Nat. Hist. 4: 470. 1844; Azolla imbricata var. prolifera Y. X. Lin; A. imbricata var. sempervirens Y. X. Lin; A. pinnata R. Brown var. imbricata (Roxburgh) Bonaparte.
Plants small, floating, outline ovate or triangular. Stems slender and creeping, lateral branches axillary, falsely dichotomous, with downward growing fibrous roots. Fronds as small as sesame seeds, alternate, sessile, imbricate in 2 rows, trapezoidal blade parted into dorsal lobe and ventral lobe; dorsal lobes green, or usually becoming purplish after autumn, oblong or ovate, cormous, colorless at margin, densely papillose, with a cavity near base containing Anabaena; ventral lobes shell-like, ± purplish red, or colorless and transparent, obliquely submersed. Sporocarps in pairs; megasporocarp small, narrowly ovate, beaklike at apex and containing a megasporangium, producing only 1 megaspore, 9 floats in 2 rows attached around megasporangium, upper 3 floats larger, lower 6 floats smaller; microsporocarps large, globose or peachlike, with a short beak at apex, exine thin and transparent, containing majority of long-stalked microsporangia and each containing 64 microspores, microspores individually embedded in 5–8 massulae, massulae with silklike hairs on surfaces.
Floating on ponds, paddy fields, irrigation ditches. Widely distributed in Chang Jiang valley region, also in Fujian, Guangdong, Guangxi, Henan, Shandong, Taiwan [Japan, Korea, C Thailand, Vietnam; Africa, Asia, Australia, Pacific islands].
The whole plant of Azolla imbricata is used as green manure and forage; it is used medicinally to induce perspiration, promote diuresis, and to treat a variety of other conditions.
This species has been long cultivated as a fertilizer (upon decomposition) in rice paddies of SE China.
Azolla imbricata is sometimes divided into three varieties. Their morphological characters and geographic distribution are presented below.
Azolla imbricata var. imbricata: Dorsal lobes of fronds turning from green to reddish from autumn to winter or during hot summertime; plants usually not or producing few sporocarps and vegetatively reproducing. Widely distributed in Chang Jiang valley region, also in Taiwan [Japan, Korea].
Azolla imbricata var. prolifera Y. X. Lin (Acta Phytotax. Sin. 18: 454. 1980; 多果满江红 duo guo man jiang hon): Plants producing many sporocarps during autumn and dying in winter, reproducing by spores in following year. Henan, Shandong.
Azolla imbricata var. sempervirens Y. X. Lin (Acta Phytotax. Sin. 18: 454. 1980; 常绿满江红 chang lu man jiang hon): Dorsal lobes of fronds evergreen; ventral lobes colorless and transparent, not purplish red. Fujian, Guangdong, Guangxi [Vietnam].
细叶满江红 xi ye man jiang hong
Plants more robust than Azolla imbricata. Lateral branches axillary, numbers of lateral branches less than fronds of stem; when growing in shallow water to wet places or plants in crowded state, stems becoming erect and dorsal lobes changing to ventral ones. Sporangium with 3 floats on exine; massulae of microsporangium covered with anchorlike hairs.
Cultivated and escaped, rice fields, ponds, ditches. Widely distributed in Chang Jiang valley region, S China, Taiwan [NE Asia, Europe, North and South America, Pacific islands].
The whole plant of Azolla filiculoides is used as green manure and forage.