The floss-silk tree* (Chorisia speciosa Saint-Hilaire) is native to Brazil and Argentina. Depending upon the authority, the genus is classified in either the Bombacaceae (kapok or bombax family) or the Malvaceae (mallow or hibiscus family); some authorities place the bombax as a subgroup of the mallows.

Floss-silk trees grow to about 15 meters (50 feet) in height; the trunks are thickened at the base. The trunk discourages most climbing animals with stout conical thorns, but apparently tree sloths are able to climb without injury. The leaves are large and palmately compound.

Like many of the mallows, the filaments of the stamens are fused into a tube. At the base of the staminal tube are five staminodes (petal-like structures derived from stamens; the five small dark notched 'petals' in the photo). The five pairs of true anthers form a ring. In Chorisia, the ring of anthers looks like a crown. The style of the pistil extends from the ovary through the tube to hold the stigma well beyond the anthers. (Compare with the hibiscus, Plant of the Week, 7/8/2002) It is thought that bats may be the major pollinators of Chorisia.

When pollinated, the tree bears seed capsules about 20 centimeters (8 inches) long. Inside the capsules are the seeds and hundreds of strands of silky floss. Like its relative the kapok tree (Ceiba pentandra) used for buoyant devices like life jackets, floss-silk had a practical use. The floss-silk provided soft, springy filler for pillows. (See Plants that Changed History, December 24, 2002)

*The photographed flower may be a Chorisia speciosa hybrid due to the fact its petals are wider than normal C. speciosa flowers or it simply may be genetic variation in the species.