Tropical pickeral weed

Pontederia rotundifolia syn. Pontederia reniformis
Aquatic
Basal
Simple
Yellow
Pink
Green

Similar in appearance to the water hyacinth but without the expanded petiole (float)

Common names 
Also known as: Tropical pickeral weed,
Family 
Pontederiaceae
Deciduous 
No
Native/Exotic 
Exotic
Origin 
Central America And South America
Notifiable 
No
Council declaration 
SIL – Special Investigation List
Known distribution 

Uncertain

Habitat 

The perennials are aquatic plants and prefer a sunny situation. Best suited to substrates with loamy, sandy-loamy or loamy clay soil with a pH between 6,5 and 7,2.

Habit 

Aquatic herb with a rounded heart shaped leaf aquatic herb, plant attached to the bed of waterways with leaves, stems and flowers emerging. 

Impact and control methods 

A competitive weed of the inland waters and artificial ponds and water masses. It has been listed as a Category 3 invader in South Africa (no further planting is allowed - except with special permission - nor is trade in propagative material. Existing plants must be prevented from spreading).

Stem and leaves 

Annual or perennial. Vegetative stem elongate, floating or on mudflats; Succulent aquatic; stems to 3 m long, prostrateor floating, finally ascending, rooting at lower nodes. Leaves emer­gent
petioles 17-54 cm long (those of the floral leafshoot as short as 5 cm long); petiole sheaths with ligule to 7.5 cmlong (those in axil of floral shoot to 24 cm long); bladesovate-cordate, reniform or sagittate,15-34 cm long, about as wideas long, the sinus open or narrow, the veins closely spaced,radiating from apex of sinus but arcuate-ascending near margin

Flowers and fruits 

Inflorescence with 3-25 flowers; peduncle pilose, 1.4-5 cm long; spathe 1.6-4.5 cm long. Flowers pilose, tube 4-8 mm long, tepals blue or white, 7-12 mm long, the central upper tepal with 2 yellow spots near the center; lower stamens 0.7-8 mm long, upper stamens 6.5-14 mm long, anthers ovoid to oblong, 0.6-1.3 mm long, larger on the longer stamens; ovary 1-2 mm long; tristylous. Nutlet about 7 mm long, including apical attenuate spine.

Reproduction and dispersal 

Predominantly seed, can spread vegetatively from fragmented rhizomes.

Similar species 

Water Hyacinth - E. crassipes is usually a free-floating plant with leaves on or above the water surface. These leaves have a thickened, spongy, stalk (petiole) and a broad leaf blade with entire margins. Its very showy flowers (4-6 cm across) are blue, purplish or mauve in colour (with a yellowish spot).