Azolla pinnata
Description
Plants triangular to trapezoidal;
Devoid of leaves except for those that subtend branches;
Distribution
Asia-Tropical: India present; Sri Lanka (Sri Lanka present), Madagascar present, New Caledonia present, SE Asia present, Wet tropical Africa present, northern and eastern Australia present, southern and eastern China present
Wet tropical Africa, Madagascar, India, Sri Lanka, southern and eastern China, SE Asia, northern and eastern Australia, and New Caledonia; in Malesia: throughout.
Taxonomy
In a recent revision of the taxonomy of Azolla pinnata three subspecies were accepted, of which only one is indigenous to Malesia: A. pinnata R. Br. subsp. asiatica Saunders et Fowler, Bot. J. Linn. Soc. 109 (1992) 349 . This subspecies possesses lax to slightly imbricate dorsal leaf lobes with narrow hyaline margins (width of leaf/width of margin = c. 9.5/1), and a megasporoderm surface of prostrate or erect elongate excrescences.
Cytology
The chromosome number has been reported to be n = 22 or 2n = 44 . Triploidy (2n = 66) and tetraploidy (2n = 88) are also reported (K.K. Stergianou & K. Fowler, l.c.; R.M.K. Saunders & K. Fowler, l.c.).
Citation
Strasb. 1873: Über Azolla: 79
Zhou 1983 – In: Rev. Palaeobot. Palyn.: 111
Fowler & Stennett-Willson 1978 – In: Brit. Fern Gaz.: 409
Sweet & Hills 1971 – In: Amer. Fern J.: 3
Ashton & Walmsley 1984 – In: Bot. J. Linn. Soc.: 242
Baker 1886: p. 100. – In: J. Bot.: repr. in Handb. Fern Allies (1887) 138
Mett. 1847 – In: Linnaea: 273
Saunders & Fowler 1992 – In: Bot. J. Linn. Soc.: 348