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PONTEDERIACEAE

Pontederia

Source:

SSA

Description:

Perennial emergent herb; stem erect, 1-leaved, with several sheathing, bract-like leaves at base. Leaves obtuse, margins entire with parallel, outwardly curved-convergent venation; blades lanceolate, ovate, cordate, sagittate, hastate or reniform; foliage dark green to greyish. Petiole of leaf of floral shoot short; petioles of other leaves long; bases sheathing and clasping, sheaths ligulate. Inflorescence a spike with few to many blue, white or white-green flowers, enclosed by a spathe and petiole base of leaf of floral shoot. Flowers irregular, bilabiate, largest perianth lobe with a bilobed yellow spot. Stamens unequal, in two groups of 3 each, adnate to perigone tube; anthers introrse, dorsifixed, versatile, dehiscing longitudinally; filaments and perigone tube covered with hairs terminating in pinhead-like glands. Ovary with 2 carpels aborted and 1 fertile, 1-locular, 1-ovulate; ovule pendulous, anatropous; placentation parietal. Fruit a 1-seeded, indehiscent nut, enclosed by a hardened perigone base, toothed, smooth or with spinulose ridges; pericarp rich in glutin. Seeds reniform or ovoid; endosperm white, copious, surrounding a cylindrical embryo. x= 8 (polyploidy).

Distribution:

Species 4, tropical to warm America, naturalised in Australia, Europe and sthn Afr.: * Pontederia cordata L. var. ovalis Solms, originally from tropical South America, is sold in local nurseries as an ornamental water plant and has become naturalised locally and may become invasive.

Monochoria

C.Presl

Source:

SSA

Description:

Annual or perennial aquatic herbs, erect, usually deciduous, rhizomatous. Leaves radical, emergent, petiolate, with cordate to ovate blade, extremely variable as to size and shape. Flowers pedicelled, racemose or subumbellate. Perianth segments free, subequal, blue, marcescent. Stamens 3 + 3, arising from base of segments, unequal, the largest with an erect tooth on one side of filament; anthers erect, basifxed, opening by apical slits. Ovary 3-locular, with axile placentas, many-ovulate; style filiform; stigma apical, small. Capsule spindle-shaped, with thin pericarp enclosed by marcescent perianth. Seeds many, minute, ovoid, with several thin ribs. x= 10, 13, 14 (aneuploids, high polyploidy).

Distribution:

Species 8, tropical Africa, Asia and Australia, naturalised in Europe; 1 in sthn Afr.: Monochoria africana (Solms) N.E.Br., only known from central and southern parts of the Kruger National Park and from a neighbouring private game reserve (Mpumalanga); apparently annual, growing in or around the edge of pans.

Heteranthera

Ruiz & Pav.

Source:

SSA

Description:

Perennial aquatic herbs, rhizomatous, rooting in mud. Leaves with long swollen spongy petiole with expanded sheathing bases; blade cordate, hastate, or ovate, or sometimes all leaves submerged and linear. Flowers small, in terminal spike, rarely 2 or solitary, occasionally some cleistogamous. Perianth nearly regular, salver- or funnel-shape, blue, accrescent. Stamens 3 (1 in cleistogamous flowers), exserted; filaments arising from throat of tube; median stamen occasionally longer; anthers dorsifixed, opening by longitudinal slits. Ovary 1-locular or imperfectly 3-locular, with 3 parietal, multi-ovulate placentas; style filiform; stigma small. Capsule oblong or terete. Seeds many, ovoid, terete.

Distribution:

Species +/- 9, tropical to subtropical regions of Africa and America; 1 in sthn Afr.: Heteranthera callifolia Rchb. ex Kunth (= H. kotschyana Fenzl ex Solms), Namibia, Botswana and from the Nylsvlei area in the Northern Province.

Eichhornia

Kunth

Source:

SSA

Description:

Perennial aquatic herbs, rooting in mud or free-floating. Roots many, long and feathery in floating plants. Leaves dimorphous; the emergent ones with often swollen, long petioles, and obovate, orbicular, spathulate or lanceolate blades; submerged leaves alternate, linear, with petioles sheathing stems, shortly stipulate. Flowers in well-developed spikes or these reduced to 1 or 2 flowers. Perianth funnel-shaped, with a somewhat curved tube and 6 subequal spreading lobes, blue or mauve. Stamens 3 + 3, upper included, lower exserted; anthers dorsifixed, oblong, opening by longitudinal slits. Ovary 3-locular; ovules many; style filiform; stigma slightly dilated, entire or very shortly lobed. Capsule spindle-shaped, covered with marcescent perianth. Seeds many, small, ovoid, finely ribbed. x= 8 (aneuploids, polyploidy).

Distribution:

Species 7, tropical America and Africa; 1 in sthn Afr.: Eichhornia natans (P.Beauv.) Solms, N Namibia and Botswana. * E. crassipes (Mart.) Solms (Water hyacinth), originally from South America, has become one of the world's worst pests of waterways; in South Africa it is a declared weed and prohibited as an ornamental plant.

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PONTEDERIACEAE