278 



HENDERSON'S HANDBOOK OF PLANTS. 



ARA 



mon in tropical countries, but rare in 

 those with a cold or temperate climate. 

 Botanists have mixed them with Oron- 

 tiads, (OrontiacefK,} from which their her- 

 maphrodite flowers distinguish them. 

 Most have tuberous roots, (corms,) but 

 some acquire the stature of little trees, 

 the most interesting of which is the Dumb 

 Cane, a species of the genus Dieffenbachia. 

 The acrid, poisonous qualities which have 

 given rise to the latter name, are charac- 

 teristic of the order. Nevertheless, 

 the whole contain starch in such 

 abundance, that it may be separated in 

 the form of Arrow-root, or used as food in 

 the combined state, only, however, after 

 very careful washing, to remove the 

 acrid juices. Thus, the common spotted 

 Arum was eaten in time of scarcity, and 

 yields a kind of Arrow-root, and the Colo- 

 casias are grown everywhere in hot coun- 

 tries as common field crops. See all 

 these names. 



One of the peculiarities of the order is 

 to extend the end of the spadix into a 

 soft, cellular, enlarged process, which is 

 the growing point of the flower branch, 

 and analogous to the succulent recepta- 

 cle of the Strawberry, the spongy excres- 

 cence called the Oak Apple, and even the 

 stiff, hard spine of the Gleditschia. 

 Scarcely more than 200 species are 

 known. The Caladium, Richardia &thio- 

 pica, (Calla,) Arum, Colocasia, etc., are ex- 

 amples of this order. 



Arachnoid. Eesembling cobwebs in ap- 

 pearance; composed of soft downy hairs 

 or fibers; resembling the web of the 

 gossamer spider; as the pubescence on 

 the leaves of Sempervivum arachnoideum, 

 Calceolaria arachnoidea, etc. 



Arachnoidem. Covered with capillary fila- 

 ments. 



ARC 



Arads. An English name for the Aracece, 

 which see. 



Araliac&x, (Araliads, Ivyworts.} These form 

 a small natural order closely approaching 

 Uinbellifers, from which they in reality 

 differ in little, except in their fruit al- 

 ways consisting of more carpels than two, 

 and having no double epigynous disk. 

 They are also more generally arborescent, 

 many of them being trees or large 

 shrubs, and very few herbs. Several are 

 conspicuous for their broad, noble foliage. 

 The species are found in the tropical and 

 sub-tropical regions of the world, and in 

 some of the coldest, as in Canada, the 

 northwest coast of America, and Japan. 

 Aralia polaris even occurs in Lord Auck- 

 land's Islands, in 50| south latitude. 

 They have aromatic qualities, usually 

 slight, but occasionally intense. One of 

 them forms a soft, white, spongy pith, 

 which, when cut into thin plates and flat- 

 tened, becomes the famous so-called Rice 

 Paper of the Chinese. Hedera, Aralia, 

 Panax, Gunnera, Adoxa, etc., are exam- 

 ples of this order. 



Araniferous. Resembling a spider. 



Ara-root.The same as Arrow-root, which 

 see. 



Arboreous. Being a tree, as distinguished 

 from frutesaent or shrubby. 



Arborescent. Having a tendency to become 

 a tree. 



Arbuscula. A small shrub with the appear- 

 ance of a tree, like many Heaths. 



Archegone. A term applied to the long- 

 necked, cellular sacs which occur in the 

 higher, or acrogenous Cryptogamia, and 

 which are analogous to the pistils of 

 Phsenogarns, (which see.) They contain at 

 the base of their cavity a cell which is an- 

 alogous to the embryo sac of Phcenogamia, 

 and which is impregnated by the agency 



