Duck Lettuce

Not yet found in Pakistan but it may possibly occur in N.E. districts of Lahore, Kasur and Sheikhupura. Stewart, l.c. found it at Gurdaspur and Koelz collected it at Keshapur (E. Punjab) near the Pakistan border.

Ottelia alismoides is a quite distinctive member of our aquatic flora. It is the only species we have with flowers surrounded by a winged or ribbed spathe. The plant is entirely submersed except for the flower, which is projected to the water surface by the elongate peduncle. The flowers may open fully even when completely submersed.

First collected in North America in Calcasieu Parish, Louisiana, in 1939, Ottelia alismoides is a conspicuous weed of rice paddies and irrigation systems in the warmer countries of the Eastern Hemisphere. Propagules were probably inadvertently brought into North America with rice seed (D. H. Dike 1969).

Root fibrous. Leaves thin, transparent, light green, submerged to partly emergent or floating, lamina variable in shape and size, submerged ones oblong-lanceolate, attenuate to short petiole, floating leaves broadly ovate to nearly orbicular, 6-20 (-22) cm long, 4.5-16 (-20) cm wide, shallow to deep cordate at the base, apex obtuse; veins 7-10, parallel convergent; petioles 8-50 cm long, triangular, with pale broad sheath at the base. Spathe elliptic-ovate, 2.5-4.5 (-6) cm long, 2-lobed, lobes acute, glabrous, lengthwise 5.10-winged or occasionally only ribbed, wings somewhat flat or wavy; peduncle; 10-30 cm long, 4-5-angled. Flowers bisexual, sessile, solitary. Sepals linear-oblong, 10-16 mm long, 2-4 mm wide, obtuse, persistent. Petals obovate or suborbicular, 2-3 mm long, 2-2.5 cm broad, obtuse, white with yellow spot at the base. Stamens 6 (-9), filaments c. 4 mm long, glandular-hairy; anthers basifixed, linear. Styles 6-9, each split into 2 unequal, papillate or ± hairy branches. Fruit rostrate, oblong-elliptic, 2-4 cm long, c. 3-4 cm in diameter. Seeds fusiform, 1-2 mm long.

Leaves submersed; blade lanceolate to widely ovate, to 17 ´ to 20 cm, margins entire to crisped. Inflorescences 1-flowered; spathes 3--10-winged. Flowers: sepals10--15 ´ 2--9 mm; stamens 3--12; ovary 1, 3--9-carpellate. Fruits 15--40 mm. Seeds to 2000.

North East Africa, Nepal, India, South East Asia, China, Japan, Australia, Solomon Islands.

Distribution: N.E. Africa eastwards to Malayasia, tropical Australia, Japan and the Solomon Islands; introduced and naturalized in N. Italy in the ricefields.

Calif., La.; Asia, Australia.

270 m

Fl. Per.: Throughout the year.

Flowering spring--summer.

Shallow water of bayous, pools, and lakes; 0--50m.

Stratiotes alismoides Linnaeus, Sp. Pl. 1: 535. 1753

Ottelia alismoides, commonly known as duck lettuce, is a species of aquatic plant native to Asia and northern Australia.