Citrullus lanatus

Scientific Name Citrullus lanatus (Thunb.) Matsum. & Nakai
Common Names English: Citronmelon, watermelon; German: Wassermelone; French: Melon d'eau, pastèques; Spanish: Sandiá
Description Annual herb with long (up to 10 m, 32.8 ft) stems lying or creeping on the ground, with curly tendrils.

Descriptions

Characteristic Features

Berry 1.5-20 cm (0.59 - 7.87 inch) in diameter, large hairy leaves.

Young Plant

The cotyledons are thick, ovate, and shiny green on the surface. The distinctive white venation is obvious. The large cotyledons are about 1.0 cm (0.39 inch) wide and 1.8 cm (0.71 inch) long. The first leaves are palmate, or nearly so.

Cotyledons

Thick, ovate, and shiny green on the surface with obvious white distinctive venation.

Stems

Hairy, tendrils at joints.

Leaves

Alternate, spiral, simple, petiolate. Petiole 18-100(-120) mm (0.71 - 3.93 - 4.72 inch) long.
Leaf blade 40-165(-200) mm (1.57 - 6.49 - 7.87 inch) long, 28-85(-150) mm (1.1 - 3.35 - 5.9 inch) wide, dissected (deeply), palmately lobed (3-5 lobed, central lobe longest).
Base tapering or cordate or hastate or auriculate or truncate.
Margins entire or crenate or dentate.
Apex acuminate or acute or mucronate or apiculate or retuse or emarginate.
Blade with indumentum. Indumentum hairy (upper surface sparsely villous; lower surface densely villous or occasionally papillose-hispid).
No hairs on leaf surface.

Propagatio Organs

Flowers

Solitary, axillary, predominantly yellow, regular, slenderly pedicellate. Pedicel 1.5-15(-80) mm (0.059 - 0.59 - 3.14 inch) long, perianth 2 -whorled.
Calyx 3-8 mm (0.12 - 0.31 inch) long, 5 sepals, all sepals joined.
Corolla 4-17(-19) mm (0.16 - 0.67 - 0.75 inch) long, 5 petals, all petals joined.
Stamens 3 (or 3 staminodes in female flowers), adnate to the perianth, all alternating with the corolla parts, free of each other.
Anthers dehiscing via longitudinal slits.
Ovary syncarpous, inferior, 1 -celled. Ovules 20-50 per cell.
Styles 1, simple (with 3-lobed stigma).

Flowering Period

May-September.

Fruit

Many-seeded berry. 1.5-20 cm (0.59 - 7.87 inch) in diameter, subglobose, greenish, mottled with darker green. Fruits vary considerably in morphology. The pulp varies from yellow or green (wild forms) to dark red (cultivars).

Seeds

Dull brown, ovate, flattened, 9-12 x 5-7 mm (0.35 - 0.47 x 0.19 - 0.27 inch). Germination in early spring.

Viability Of Seeds

Short lived in soil seed bank.

Propagation

By seeds.

Occurrence

Habitat

Grassland or bushland, often along watercourses.

Soil

Well drained soil, gravely soil, sand, loam, clay.

Agricultural Importance

C. lanatus is difficult to control with most available preemergence herbicides currently registered in cotton. Citronmelon can be a problem weed in peanuts. It is resistant to shade and classified as a noxious weed in Australia.

Control

Integrated Crop Management

Intercropping and mechanical interrow weed control methods result in good control of this weed.

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