ABALES. 461 



Ornitliogalum unibellaium, the Star of Bethlehem, is a native of Cen- 

 tral Earope. 



Polianthes tuherosa, the Tuberose, a native probably of the East 

 Indies, bears a tall spike of fragrant white flowers. It is sometimes 

 placed in the order Ainaryllidaceae. 



Buscus aculeatus, the Butcher's Broom of England and Southern 

 Europe, a curious shrub, with flat leaf-like branches, is rarely cultivated 

 with us. 



Tritoma uvaria, of the Cape of Good Hope, bears a tall spike of red 

 flowers, and hence receives in cultivation the name of the " Red-Hot 

 Poker Plant." 



I'ulipa Oesneriana, the Tulip, is a native of tlie Levant. It was 

 brought into Europe about three hundred years ago, and originally 

 bore yellow flowers, but under long culture it has developed number- 

 less varieties. To the Dutch we owe much of the improvement in this 

 flower ; in the first half of the seventeenth century throughout Holland 

 so much attention was given to its culture, and such high prices paid 

 for single bulbs of the finer varieties, that a speculative mania (known 

 aa the " tulipomania") arose, resembling the wildest of modern grain 

 or stock manias. 



Tueca, of several species, known by the name of Adam's Needle, 

 Spanish Bayonet, Bear Grass, etc., is a. genus of fine ornamental 

 plants, natives of the warmer parts of America. The strong fibres are 

 sometimes made into cordage. The roots contain saponin, and are 

 used by the Mexicans instead of soap for washing. 



Xantliorrlma includes the curious Grass Gum Trees of Australia. 



557.— Cohort VI. Arales.— A group of dissimilar plants, 

 some being large trees, and others microscopic floating herbs. 



Order Lemnaceee. — The Duckweeds. These smallest of Phanero- 

 gams consist of floating disks (thalli), with no distinction of leaf and 

 stem, bearing one or several roots beneath (in Wolffia, hovpever, no 

 roots). They are parenchymatous throughout, or with only rudiment- 

 ary vascular tissues. Their flower-clusters are sunken into pits in the 

 top or edge of the disks, and consist of one or two stamens and a single 

 pistil, representing as many reduced flowers. There are about twenty 

 species, widely distributed throughout the northern hemisphere. We 

 have eight or ten species in the United States. (Figs. 350-3.) 



Order Aroldese. — The Arum Family. Herbs often large and palm- 

 like in appearance, with large leaves having reticulated venation. In- 

 florescence generally surrounded by a spathe. Of the Aroids there are 

 about 1000 species, distributed mostly in tropical countries, where they 

 sometimes attain a height of several metres (6-12 feet) ; in temperate 

 climates they are much smaller. They possess an acrid juice, which 

 may be poisonous. 



