Common Water Hyacinth

The entire plant is used for fattening livestock, and as green manure. The young leaves and petioles are sometimes used as a vegetable.

The ‘Water Hyacinth’ is very common in the Punjab, especially in the Gujranwala district, inhabiting vast marshy areas, propagating by stolons and multiplying very fast. It covers vast areas of water forming impenetrable growth. The lilac flowers are a beautiful sight during the flowering season. Difficult to eradicate and due to its quick growth, it has become a troublesome weed around Lahore, especially in the Gujranwala district. The plant is rich in potash.

This is probably the most aggressive aquatic weed ever known in the tropics (T. D. Center and N. R. Spencer 1981; R. E. Fitzsimons and R. H. Vallejos 1986; W. T. Penfound and T. T. Earle 1948; H. J. Webber 1897) and has been documented to cause extensive physiological changes in the aquatic environment (G. R. Ultsch 1973). It is on the USDA/APHIS noxious weeds list and the Florida Department of Natural Resources prohibited list (D. C. Schmitz 1990). Extensive research has gone into pesticide and biological control (R. G. Baer and P. C. Quimby Jr. 1981; T. D. Center and T. K. Van 1989; J. C. Joyce and W. T. Haller 1985; D. C. Schmitz 1990), resulting in its decline in Florida. Plants were probably first introduced into the U.S. at the Louisiana exposition in 1884 (W. T. Penfound and T. T. Earle 1948), and the species is now known in all states where freezing temperatures are minimal. Research results from the 1970s suggest that the species may have an economic importance by removing toxic substances from water (F. Chigbo et al. 1982).

The inflated petiole has long been a characteristic used to separate Eichhornia crassipes from other species of the genus. Yet on older plants under crowded conditions, the petiole shows little or no swelling (W. T. Penfound and T. T. Earle 1948). This has resulted in several misidentifications of specimens as E. azurea. Inflorescences typically elongate overnight, and all flowers open the same day (W. T. Penfound and T. T. Earle 1948). However, some robust specimens have inflorescences in which the proximal flowers open the first day and the distal 2–4 flowers open on the subsequent day. Individual flowers open shortly after dawn and wilt by nightfall. By the next morning, the flowering stem has bent such that the developing fruits are typically submersed, allowing seed development to occur under water (W. T. Penfound and T. T. Earle 1948). S. C. H. Barrett (1977, 1979, 1980, 1980b, 1988, 1989) has studied the reproductive biology in depth. The water hyacinth is a tristylous species; however, the only naturally occuring populations with all three morphs are in northeastern Brazil. This led S. C. H. Barrett and I. W. Forno (1982) to conclude that Eichornia crassipes is native to Amazonia. All other studied populations in the world have only one or two of the floral morphs. In some populations, a breakdown in the tristylous condition was observed whereby the stigma was found to be adjacent to anthers in some flowers (semihomostylous condition), resulting in some seed production (S. C. H. Barrett 1979). In general, seed production in temperate populations was found to be half that of tropical populations, mainly due to differences in levels of insect visitation (S. C. H. Barrett 1980b).

30-50 cm high herb, with short stem and many long fibrous roots, floating or sometimes rooting. Leaves glabrous, 45-110 x 50-100 mm; broadly ovate to rhomboid, entire, obtuse, base cuneate or rounded. Petiole glabrous and spongy, 6-30 cm long, with a fusiform bulbous portion about the middle. Peduncle spongy. Inflorescence (3-)6-15 (-35) flowered. Flowers lilac, tinged blue, withering soon. Perianth c. 57 mm long, tube green, glandular; segments 34-40 mm long, obovate to ovate-oblong, posterior segment with a yellow spot. The longer 3 stamens c. 21 mm, filaments curved, glandular hairy;shorter filaments c. 6 mm long, glabrous; anthers purple-blue. Ovary ovoid, glabrous; style glandular; stigma 3-lobed, glandular.

Herbs floating, 0.3--2 m. Roots many, long, fibrous. Stems very short; stolons greenish or purplish, long, apically producing new plants. Leaves radical, rosulate; petiole yellowish green to greenish, 10--40 cm, spongy, usually very much swollen at or below middle; leaf blade orbicular, broadly ovate, or rhomboidal, 4.5--14.5 × 5--14 cm, leathery, glabrous, densely veined, base shallowly cordate, rounded, or broadly cuneate. Inflorescences bracteate, spirally 7--15-flowered; peduncle 35--45 cm. Perianth 6-parted, segments purplish blue, petaloid, ovate to elliptic, upper one larger with yellow blotch at center adaxially, others subequal but lower one narrower. Stamens 6, 3 long and 3 short; filaments curved, glandular hairy. Pistil heterostylic; stigma glandular hairy. Capsule ovoid. Fl. Jul--Oct, fr. Aug--Nov.

Plants perennial, typically free-floating. Vegetative stems condensed, except when branching. Flowering stems erect, bending over after flowering, to 25 cm, distal internode less than 4 cm. Sessile leaves in basal rosette. Petiolate leaves floating or emersed; stipule 2.5–14 cm, apex truncate; petiole at least slightly swollen, 3.5–33 cm; blade ovate to round, 2.5–11 × 3.5–9.5 cm. Spikes 4–15-flowered; spathes obovate, 4–11 cm; peduncle 5–12.5 cm, glabrous. Flowers opening individually within 2 hours after sunrise, wilting by night; perianth blue or mauve-blue, limb lobes obovate, 16–37 mm, margins entire, central distal lobe with dark blotch in center and yellow spot within blotch; proximal stamens 20–35 mm, distal 14–19 mm; anthers 1.7–2.1 mm; style 3-lobed. Seeds 11–14-winged, 1.1–2.1 × 0.6–0.9 mm. 2n = 32.

Anhui, Fujian, Guangdong, Guangxi, Guizhou, Hainan, Hebei, Henan, Hubei, Hunan, Jiangsu, Jiangxi, S Shaanxi, Shandong, Sichuan, Taiwan, Yunnan, Zhejiang [native to Brazil; widely introduced and naturalized in tropics and subtropics].

S. America, naturalised widely in Asiatic Tropics.

introduced; Ala., Ariz., Calif., Fla., Ga., La., Miss., N.C., S.C., Tex., Va.; worldwide, tropics and subtropics.

Distribution: Native of Brazil, introduced and naturalised in many tropical countries.

200-1500 m

Fl. Per.: May July.

Flowering early spring--late fall.

Ponds, ditches, canals, calm waters of rivers; 0--300m.

Naturalized, growing gregariously in pools, ditches, and rice fields; 200--500 m.

Pontederia crassipes Martius, Nov. Gen. Sp. Pl. 1: 9, plate 4. 1823; Eichhornia speciosa Kunth; Piaropus crassipes (Martius) Rafinesque

Pontederia crassipes Martius, Nov. Gen. Sp. Pl. 1: 9. 1823; Eichhornia speciosa Kunth; Heteranthera formosa Miquel.