Sel Serat Kapuk Randu (Ceiba Pentandra)

Sel kapuk randu seperti halnya sel kapas berbentuk memanjang, perbedaannya; pada sel kapuk tidak terdapat torsi, sehingga sel kapuk hanya berupa lumen (rongga sel) yang dibatasi oleh dinding sel dengan lingkungan luar. Oleh karena itu sel kapuk mampu menyimpan udara sehingga baik digunakan sebagai bahan isolasi. Serat kapuk banyak digunakan sebagai bahan kasur atau bantal. Biasanya, kasur jika telah lama digunakan, maka sel-sel kapuknya akan terisi minyak yang berasal dari keringat kita, sehingga tidak empuk lagi. Oleh karena itu, kasur tersebut harus dijemur di bawah terik matahari, untuk menguapkan minyaknya, sehingga dapat dipakai kembali.

Serat kapuk berasal dari sel epidermis dari kulit buah. Sel-sel ini mulai tumbuh kira-kira 16 hari sesudah pembungaan, yaitu waktu pembelahan sel telur dan ada kepastian buah tidak rontok. Serat yang sudah tua membentuk lumen yang kosong berdinding tipis dan terisi udara serta tertutup pada kedua ujungnya. Dindingnya licin dan dilapisi lapisan lilin sehingga serat kapuk sangat ringan dan mempunyai kemampuan mengisolasi panas dan suara. Dinding serat kapuk licin dan tidak terpilin sehingga serat kapuk sulit dipintal menjadi benang karena antara serat yang satu dengan yang lain tidak melekat menjadi satu.

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The Kapok Tree

A great natural resource.

The kapok tree, also known as the silk cotton tree, is native to New World and to Africa and was transported to Asia where is cultivated for its fiber, or floss. The kapok's huge buttressed trunk tapers upwards to an almost horizontal, spreading crown, where large compound leaves are made up of five to eight long, narrow leaflets. In full sun, the kapok can grow up to 4 meters (13 feet) per year, eventually reaching a height of 50 meters (164 feet).

The kapok tree is deciduous, dropping its foliage after seasonal rainy periods, thus ridding it of damaged leaves while purging the tree of fungi, herbivorous insects, and other organisms. This loss of leaves also improves access for the bats that feed on the sugar-laden nectar of kapok blossoms. In doing so, the bats unwittingly pollinate the tree's flowers. The flowers open at night and have five petals that are white or pink on the outside. Only a few flowers on a given branch will open on any particular night during the two or three weeks that the tree blooms.

Kapoks do not bloom every year, and some may go 5–10 years without flowering. When the tree does bloom, however, it is prolific, producing up to 4,000 fruits measuring up to 15 cm (6 inches) long. Eventually these pods open on the tree, exposing the pale kapok fibers to the wind for dispersal. The fibers, in which over 200 seeds are loosely embedded, are sometimes referred to as silk cotton and are yellowish brown, lightweight, and lustrous.

In harvesting of the great kapok fiber, the pods are either cut down or gathered when they fall, then broken open with mallets. The seed and fiber, removed from the pods by hand, are stirred in a basket; the seeds fall to the bottom, leaving the fibers free. The seeds may be processed to obtain oil for making soap, and the residue is used as fertilizer and cattle feed.

Although kapok wood does not hold screws or nails well, the timber is used for a variety of wood products, including paper. Local peoples have long used kapok logs for carving into canoes. The genus name of the true kapok, Ceiba, likely derives from a Carib word for a dugout boat.

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