Ceiba speciosa Seeds | Silk Floss Tree
LATIN NAME: Ceiba speciosa
COMMON NAME: Silk Floss Tree
Plant Profile
Ceiba speciosa is a street tree in Buenos Aires and a forest tree in the Paraná basin, and it is hard to mistake in either place. The trunk is green when young and studded with stout conical spines, and it broadens into a bottle shape that stores water through the dry season. Older trees lose most of the spines and take on a grey, smooth bark that looks poured rather than grown.
The flowers open in late summer before the leaves, five pink petals around a dark centre, and they are followed by leathery capsules the size of a fist. When those split, the seed is packed in a mass of white fibre that spills out and drifts, which is where the common name comes from. The fibre is the reason the tree was planted widely beyond its range in the nineteenth century.
Science & Biotechnology
The floss is a seed hair, not a bast fibre, and that distinction decides what it can be used for. Each hair is a single elongated cell with a thin wall, so it collapses and mats rather than twisting into a thread. Kapok from the related Ceiba pentandra was used for life jackets and mattresses for exactly this reason: it is light, water-repellent and cannot be spun on its own.
The seed carries a fatty oil with unusual cyclopropenoid acids, malvalic and sterculic, which are the same compounds found in cottonseed and which cause the pink discolouration in stored eggs when the meal is fed to hens. The tree also produces a gum from wounds in the bark, and the green trunk carries out photosynthesis while the tree is leafless.
Uses & Benefits
The fibre fills pillows, life jackets and upholstery, usually blended with cotton or polyester because it has no crimp and packs down. The seed is pressed for oil in small quantities, and the pressed cake is fed to cattle only after the cyclopropenoid content has been considered, since it is not a free ingredient in a dairy ration.
In South America the tree is grown mainly for ornament, and the timber is light and used for boxes and plywood cores. Extracts of the bark appear in local medicine as a wash for wounds, and the gum is chewed in some districts, though neither use has been through a modern trial.
Growing from Seed
Seed is short-lived and should be sown within a few months of collection. Soak it for a day in warm water, then press it into a free-draining mix at 25 to 30 degrees, and it usually comes up in two to four weeks. The seedling grows fast and can reach a metre in its first season, but it is tender and needs a warm, sheltered spot until the trunk has thickened.
The tree wants full sun and room. It tolerates drought once the bottle-shaped trunk has formed, and it tolerates poor soil, but it does not tolerate being moved, because the taproot is long and soft. Plant it small, stake it for the first two years, and keep the spines in mind when siting it beside a path.
Our Take
A dramatic tree for a warm garden, grown as much for the spiny green trunk as for the late pink flowers. Give it space and do not move it.
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