5o 



BRITISH FLOWERING PLANTS 



but should not be eaten freely, as this is due to 

 the presence of oxalic acid, a deadly poison which, 

 when concentrated, is often improperly called 

 " salts of lemon." 



The ripe seed-capsules of both species of Oxalis 

 split open and scatter their seeds, when touched, 

 as in the case of the Yellow Balsam, already 

 noticed. 



Order XXII. Linacece (2 genera) 



Flax — Linum usitatissimum 



(Plate XXI) 



Flax is cultivated in some parts of the country, 

 but is also found occasionally growing wild. It is 

 an annual, and grows to the height of two or three 

 feet, the stem being set round with narrow pointed 

 leaves, smooth, undivided, and sessile, of a 

 greyish green colour. As the plant ripens, the 

 leaves drop off. At the top the stem branches out, 

 and bears bright blue flowers, on slender stalks, 

 which flower in June and July. The calyx is 



short, with 5 lanceolate sepals ; there are also 5 

 petals, and as many stamens. The fruit is a 

 capsule, imperfectly divided into 10 carpels, each 

 of which contains a seed. The capsule is nearly 

 round, pointed above, and ripens in August 

 and September. The shining brown oval seeds 

 are called linseed. There are several varieties of 

 Flax, and the wild plant does not grow so high as 

 the cultivated forms. Sometimes the capsules are 

 allowed to explode in the sun and scatter the seed, 

 and sometimes the plant is threshed out. The 

 stalks have to undergo several processes before 

 thread can be prepared from them, ready for 

 spinning. They are first steeped, to rot the woody 

 portions, and are then dried, broken up, and the 

 woody particles removed by combing, or "carding" 

 as it is called. The remaining silver-grey fibre is 

 spun into thread. Linseed-oil is pressed out from 

 the seeds, which are then used for cattle-food, under 

 the name of " oil-cake." 



Flax-seed is used to make "linseed tea" for 

 colds and coughs, and when crushed is used for 

 poultices. Linseed oil is much used for lubricating 



