HELIOPHILA ARABOIDES. 145 



HELIOPHILA ARABOIDES. 



Arabis-like Heliophila. 

 Linnean Class — Tetradynamia. Order — Siliqtjosa. Natural Order — Crucifer;e. 



The plants of the Natural Order Crucifera, or Cabbage tribe, are, in general, more 

 remarkable for their culinary and economical uses, or for their troublesome 

 character as weeds, than for their adaptability to decorative gardening. 



The beauty of the various species of "Wallflower and Double Stock is, however, 

 amply sufficient, in the eyes of the Florist, to redeem the Order from the charge of 

 want of interest ; and these, with the Sockets, Candy-tufts, and a few members 

 of the genera Alyssum, Arabis, Aubrietia, and JEbhionema, may be said to 

 constitute its chief attraction in an horticultural point of view. To these we 

 may add, among annual plants, the curious Schizopetalon WalJceri, the Erysimum 

 Petroffskianum, and last and least in size — though not in interest — the little 

 Heliophilas, remarkable as being one of the very few genera of Cruciferous 

 plants yielding flowers of a pure blue tint. This circumstance, as well as their 

 comparative rarity in our gardens, has induced us to figure one of the species 

 as an illustration of the Order. 



The Cruciferce, as our readers know, are so named from the resemblance their 

 four petals are supposed to bear, when fully expanded, to a Greek cross— whence 

 the English name Cross-wort. This, however, is not their most remarkable 

 feature, which consists rather in the tetradynamous character of their stamens. 

 Four of these are arranged in two opposite pairs, the remaining two bein» 

 solitary, and usually more or less shorter than the others. The filaments are 

 frequently furnished with teeth or processes near the base; sometimes these 

 occur only on the solitary stamens, as in the genus Heliophila; in others, only 

 on the longer pairs, as in the little Schiverechia podolica, where it appears in a 

 wing-like form on each side of the filament. The long narrow pod, or siliqua, is 

 another peculiarity of this Order, and with the four petals and tetradynamous 

 stamens, readily distinguish it from all others. Sometimes, however, the ovary 

 instead of being lengthened out, as in the Stock and many other genera, is 

 short and broad, as in the Candytuft, in which case it is termed a silicule. 

 Perhaps one of the most curious features of the Cross-worts is the manner 

 in which the cotyledons or seed-lobes are folded in their narrow cell, though 

 we fear explanations would hardly be intelligible without a liberal use of 

 wood-cuts. The convolutions of the fire-work commonly termed a serpent 

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