Floss Silk Tree
One of the most spectacular tropical, deciduous, flowering trees that I know has just started to flower in the gardens here. Called the Floss Silk Tree (Ceiba speciosa syn Chorissia speciosa), it comes from Brazil and Northern Argentina where it can grow into a big tree over many years. This beautiful genus was cultivated by the South American indigenous peoples long before the arrival of Europeans.
The Floss Silk Trees are hardy trees which can withstand light frosts, droughts, wind and even coastal conditions. I have been told of one growing close to the sea at Ruakaka and doing well. They do best in free-draining soils with reasonable fertility. An occasional water during the summer dry will make them grow very quickly.
The first thing one notes when standing beside the trees is the thick based, conical spines which cover the trunks and can extend onto the branches of some of the trees. Each tree has a different coverage of thorns; some trees lack thorns entirely. The other thing that stands out is the green bark, even on the main trunk, which means that the tree has enough chlorophyll to carry on growing over the winter months. Growth in this instance means adding girth to the trunk and branches and by the end of the winter one can see the stretch marks on the bark. With time these trunks develop buttress roots.
When the leaves start growing in the spring the branches start elongating so the tree grows larger. If the tree is young another growth flush occurs in the autumn but if mature, flower buds form and then a spectacular display of large, generally pink, but sometimes red to white, flowers with cream throats appear and cover the tree for up to three months. To set off this display, Monarch Butterflies are attracted to its nectar. The flowers are 10 to 15 cm across, in pink shades with a cream throat speckled with brown spots and can completely cover the tree for many weeks. The flowers are not self-fertile so two or more trees are needed for pollination . The sexual parts of the flower are a long way from the nectar that the bees and the bumble bees like so they don’t do a natural pollination. I thought maybe in its native habitat that bats or hummingbirds would do the trick, then I noticed some high up flowers setting pods and around the same time I saw monarch butterflies being attracted to the nectar – a big insect able to do the pollination!! I wonder if they act as pollinators in South America on their yearly migration back to Mexico? The Floss Silk Tree with its nectar may be a bonus to our local monarch population.
After pollination a 20cm pod forms over the winter months and matures in October/ November. To release the seeds the thick husk splits open and falls to the ground leaving a hard, tight, white ‘cob’ which over several days starts to fluff up until it is about five times the volume of the original. The wind now starts to gradually tease out the fluff or kapok and blow it away carrying the relatively big seeds a short distance with it. It seems that this kapok (which used to be used for pillows and particularly life jackets for boats) is not of the highest grade, the true Kapok Tree Ceiba pentandra being best, but one person looking at it thought it should spin quite well. It has a beautiful crimp and sheen to the threads. More than one tree is needed for pollination and only a few pods are set by the Monarchs so there won’t be much kapok for an industry!
I have seen reference on the net that the wood is nearly as light as balsa though I have never cut any myself.
This is a handsome tree for a bigger space, not one for the smaller home garden. Enjoy them when you see them in flower where they have space to grow into a mature specimen.