282 ECONOMIC BOTANY. 



260. Many other plants produce hairs which often find 

 an economic use. The substance called Pulu, which is 

 used somewhat in upholstery, consists of the long woolly 

 hairs of several species of Fern, Dieksonia (family Fili- 

 ces), growing on the Sandwich Islands. On a Fern of 

 the Azores, Balantium caleita, beautiful, soft, silky hairs 

 grow, used by the natives for stuffing cushions. Several 

 species of Asclepias (family Aselepiadaceie) have long hairs 

 on their seeds, but they have been found to be too brittle 

 to come into extended use in spinning. The seeds of Beau- 

 montia grandiflora, of the Dogbane family (Apocynaoece), 

 have lustrous, slightly yellowish, hairs, which, like the 

 preceding, are used in upholstery, or mixed with cotton. 

 All kinds of vegetable silk (or hairs) can be readily dyed. 



261. The fibre longest used in spinning, namely. Flax, 

 is the bast of Linimi usUatissiniitm, a species of the Flax 

 family {Linacece). It is a slender annual, growing from 

 two to six feet high, and has small, alternate, lanceolate 

 leaves, and blue flowers. It probably came originally from 

 the Caucasus, or from Eastern Asia. It is extensively 

 cultivated in many lands ; other species are found in culti- 

 vation, but to a very limited extent. In warm regions 

 more seeds and less fibre, and in colder regions more 

 fibre and less seed, are produced. The Flax is harvested 

 before the seeds are ripe, when the bast at the base 

 of the stem begins to turn yellow ; later, lignification 

 sets in, to the detriment of the fibre. The unripe seeds 

 may be used for oil, but not for planting. The plants are 

 pulled out of the ground, and subjected to a process of 

 retting, either by dew, cold or warm water, or steam, by 

 means of which the bast is loosened from the stem, and 

 more or less decomposed into fibres. These are 8-55 inches 



