Calotropis procera aka French Cotton

Calotropis procera is an evergreen shrub. It belongs to the Apocynaceae family. Its common names include roostertree and small crownflower. Giant milkweed is another name. Its native range runs from Macaronesia across Africa to Indo-China. It grows in deserts, dry scrub, and other open ground. It has spread beyond this range to many warm places. These include Australia and islands in the Caribbean. It also grows in California and Hawaii.

The plant grows upright, and its branches spread outward. In gardens, it reaches 6–8 feet (1.8–2.4 metres) tall. Its spread can reach 8 feet (2.4 metres). Other sources give heights of around 13 feet (4 metres). Some reports give heights near 16 feet (5 metres). It may form a small tree with one clear trunk. Its leaves stay on the plant all year. The stems hold milky sap that poses serious hazards.

The flowers range from pale purple to white. They bloom in seasons, with no stated range of months. Both flowers and fruit add interest to the garden. Butterflies visit the plant. Insects pollinate its flowers. Ripe seed pods split and release seeds into the wind. This helps it spread far beyond where it was planted. It can invade pastures, grazing land, and hay fields. It also spreads onto roadsides and fields no longer in use.

Grow it in full sun or some shade. It copes with poor soil, salt, and dry conditions. In gardens, soil can be dry to somewhat moist. Once plants settle in, they resist drought and need little care. It survives winters outdoors in USDA zones 10–11. In colder places, gardeners can grow it in pots. Keep those pots indoors for shelter through winter. In warm gardens, it serves as a hedge or small tree. Remove pods as they grow, before they open. This limits the spread of seeds. Few pests or diseases cause serious harm. Aphids can strip its branches, though.

The stems yield strong fibre for rope, nets, and paper. Other uses include charcoal, stuffing, and green manure. People also use it to bind soil. Sources record many uses in traditional medicine, too. These uses do not make it safe to handle or eat. Its poisonous latex holds calotropin, which can harm the heart. Sap can cause severe swelling in the eyes and irritate skin. Reports describe food uses for young shoots, leaves, and sap. Those reports clash with warnings that all parts are poisonous.