Delaware County Cooperative Extension

Heliotropium indicum L. – Indian Heliotrope

This plant, although not a common weed in Oklahoma, is one that has appeared in many sites this year. It is an introduced species to the US. Questions still exist if it is native to India (part of the common name) or from tropical America as other researchers believe. Regardless, it grows well in moist sites and even frequently flooded areas. Although considered a wetland plant it rarely is found in standing water, rather invading bare soil after water recession. It can most often be found in clayey bottoms and other disturbed and exposed sites. This plant is an erect annual that grows up to 3 feet in height. The leaves, which somewhat resemble a crinkled pigweed leaf 3-15cm long, can be arranged opposite or alternate. They are shallow toothed on the margin, densely hairy on both upper and lower surfaces and ex-tend down the petiole forming “wings”. Stems are grooved and covered with coarse white hairs. Likely the most identifying characteristic is the flower, which is mostly lavender colored and born on a long, curved one-sided spike with each flower having 5 sepals. Youngest flowers are towards the tip. Rarely found in densities that warrant chemical control, little data is available on chemical susceptibility. Kostermans et al. (1987) indicated moderate susceptibility to 2,4-D when very small, while Lorenzi and Jeffery (1987) reported that 2,4-D + dicamba exhibited good control at young stages. Control after flowering has begun is likely more difficult.

Warnings: All parts of the plant are toxic, whether cured as hay or fresh. The greatest risk of poisoning is for cattle through pyrrolizidine alkaloids, although horses, chickens, pigs and humans can all be vulnerable. Sheep seem to be less affected. These alkaloids are a slow acting liver toxin and can cause atrophic hepatosis (liver damage) in cattle.

Brian C. Pugh, NE Area Agronomy Specialist OSU Extension

 

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