Spirodela polyrhiza

Content

Description

Ovary with 1 amphitropous ovule or 2 anatropous ones. Fruit a 1-2 seeded utricle, slightly winged. Seed smooth.

Distribution

Africa present, Almost cosmopolitan present, Asia-Tropical: Malaya (Peninsular Malaysia present); New Guinea present; Philippines (Philippines present); Sumatera (Sumatera present), Australasia, Flores Sea present, Hawaian Is.i present, Luzon present, Mindanao present, N. Celebes present, South America present, Tanah Djampea, S of Celebes present, W.-E. Java present, northern hemisphere present

Almost cosmopolitan, common in the northern hemisphere, rather rare in Africa and Australia, in South America replaced by two closely related species; in Malesia common: Sumatra, Malay Peninsula, W.-E. Java, Flores Sea (Tanah Djampea, S of Celebes), N. Celebes, Philippines (Luzon to Mindanao), New Guinea. Also in the Hawaian Is.i (1895 HELLER; 1927 LE ROY TOPPING), together with Lemna perpusilla.

Notes

Like many other Lemnaceae this species often forms resting-buds to survive less favourable times. In S. polyrhiza these resting-buds are easier to distinguish from the normal fronds than in the other Lemnaceous species and are often called 'turions'. They are produced in the normal way in the budding pouch. The turion is reniform, dorso-ventrally flattened, variable in size, consisting of dense tissue. Its roots are still present but when dormant only the primary roots are visible. On both sides it bears a membranous scale as does a normal young frond.

Citation

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HUNDLEY & U CHIT Ko Ko 1961: List trees etc. Burma, ed. 3. p 292

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