Myriophyllum tetrandrum

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Myriophyllum tetrandrum


Aquatic or semiterrestrial. Flowers solitary, ± sessile in the middle and upper leaf-axils, ☿, or the upper ♂. Sepals triangular, 0.1-0.3 by 0.1-0.3 mm, entire or finely serrate, acute, erect. Petals almost entire, c. 1(-1½) mm long, caducous after anthesis. Stamens 4; Fruit cruciform, c. 2 by 2 mm, mericarps ± ovate, with convex back and ± flattened sides, irregularly and finely tuberculate to smooth.


Agartala present, Asia-Tropical: Assam (Assam present, Manipur present); India (Bihar present, Uttar Pradesh present); Malaya (Peninsular Malaysia present), Bangtapan Noi present, Eastcoast from Ganjam southwards present, Kangar present, Kashmir present, N. & E. India present, North Vietnam present, Perlis present, S. Thailand present, Ta Samet present, W. Bengal present
N. & E. India (Kashmir, Uttar Pradesh, Bihar, W. Bengal, Assam, Agartala, Manipur, Eastcoast from Ganjam southwards), S. Thailand (Bangtapan Noi: Ta Samet), North Vietnam; in Malesia: Malay Peninsula (Kangar; Perlis). .


The species was in the past seldom recognized by Indian botanists and mostly reduced to M. indicum, following CLARKE (), sometimes to M. tuberculatum. Although they differ in the number of stamens, I believe it to be much closer allied to M. indicum WILLD. than to M. tuberculatum ROXB., which has the same number of stamens. M. tetrandrum and M. indicum can only be distinguished in flowering material, the fruits and bracteoles showing no differences. As M. indicum and M. tetrandrum are replacing, M. indicum being confined to Ceylon and the South Deccan and M. tetrandrum to NE. India and Indo-China, I have originally assigned them subspecific rank, but as according to PRAGLOWSKI () their pollen shows distinct differences, I have concluded that they are closely allied but distinct species.
A record from Java (, ZOLLINGER 883) belongs to Limnophila (Scrophulariaceae).


SUB-RAMANYAM 1962: Aq. Ang.: 17
S. R. BENNET 1968: Tax. Stud. Fl. Howrah (Thesis): 651
DC. 1828 – In: Prod.: 69
KENG 1970 – In: Mal. Nat. J.: 123
Roxb. 1970 – In: Fl. Thail.: 2
CRAIB 1931 – In: Fl. Siam. En.: 591
GUILLAUMIN 1920 – In: Fl. Gén. I.-C.: 717
MEIJDEN 1969 – In: Blumea: 308
PRAIN 1908 – In: Rec. Bot. Surv. India: 210
TARDIEU-BLOT 1965 – In: Fl. Laos, Camb. & Vietn.: 125
Roxb. 1832 – In: Fl. Ind., ed. Carey: 451
SCHINDL. 1905 – In: Pfl. R.: 96
W. & A. 1834: Prod.: 399