BOTANY. 177 



the binoxalate of potassa which it contains. Some species yield tubers 

 which have been used as substitutes for potatoes. 



Oxalis acetosella, Wood Sorrel (Europe and America) {pi. G7, ßg. 10) ; 

 a, plant with the rhizome ; 5, petal ; <?, stamens ; <7, capsule ; <', do. burst; 

 f^ cross-section ; g-h^ seed. 



Order 172. Balsaminace^, the Balsam Family. Sepals five, irregular, 

 deciduous, the two inner and upper connate, colored, the lower (odd) sepal 

 spurred ; sestivation imbricated. Petals alternate with the sepals, usually 

 four, in consequence of one being abortive, often more or less irregularly 

 united ; aestivation convolute. Stamens five. Ovary five-celled ; ovules 

 usually numerous ; stigma sessile, more or less five-lobed. Fruit a five- 

 celled capsule, opening septifragally, by five elastic valves. Seeds usually 

 numerous, suspended, exalbuminous, with a straight embryo, and radicle 

 next the hilum. Succulent herbaceous plants with watery juice, having 

 simple, opposite, or alternate, exstipulate leaves, and axillary irregular 

 fiowers. They inhabit chiefly the East Indies, and are remarkable for the 

 force with which the seed vessels open when ripe. The valves give way 

 on account of the exosmose which goes on in the cells, and they then curl 

 up in a peculiar manner. They have usually showy flowers, but their 

 properties are unimportant. Lindley mentions two genera, including 110 

 species. Examples : "Tmpatiens, Hydrocera. The sole North American 

 representatives are two species of Impatiens, known as glass weed, and 

 considered by some of the Indian tribes as eflScacious in the bite of rattle- 

 snakes. 



Order 173. Linace^e, the Flax Family. Sepals three, four, or five, 

 persistent, with an imbricated aestivation. Petals three, four, or five, 

 fugitive, ungpiculate, hypogynous, with a twisted aestivation. Stamens 

 equal to the f)etals and alternate with them (with intermediate teeth or 

 abortive stamens), arising from a hypogynous annular disk ; anthers ovate,, 

 erect. Ovary with as many cells and styles as sepals, seldom fewer; 

 stigmas capitate ; ovules anatropal, pendulous. Fruit a plurilocular capsule, 

 pointed generally with the indurated base of the styles ; each loeulament or 

 cell more or less completely divided by a spurious dissepiment, arising from 

 the dorsal suture, and opening by .two valves at tlie apex. Seeds solitar\ 

 in each spurious cell, compressed, pendulous ; albumen usually in small 

 quantity, sometimes 0; embryo straight; cotyledons flat; radicle next the 

 hilum. Annual and perennial plants, with exstipulate, simple,, entire leaves, 

 which are usually alternate. They are scattered over the globe, but an- 

 said to be most abundant in Europe, and in the north of AiHca. By some 

 authors the order is associated with Geraniaceae, from which it differs in its 

 unbeaked fruit and exstipulate leaves, as well as the absence of joints in th^r- 

 stem. There are three genera mentioned by Lindley, comprising ninety 

 species. Examples : Linum. Radiola. There are six JSTorth American 

 species of Linum. The principal plant of the order is Linum usitatissimum. 

 or the Flax plant. Flax is the woody fibre procured from the inner bark of 

 the stalk, by steeping and stripping off the outer bark. When worked up 

 it forms tlie various linen fabrics. Mummy cloth is made of linen, as is 



ICONOGRAPHIC ENCYCLOP..EDIA. VOL. U. 12 \11 



