363 
Alliance II. ARALES. 
Essential Character. — Flowers on a spadix. Fruit either berried or capsular. 
Order CCLXI. ARACE^E. The Arum Tribe. 
AROiDEiE, Juss. Gen. 23. (1789); R. Brown Prodr. 333. (1810); DC. and Dufty, 480. 
(1828) ; Lindl. Synops. 246.(1829) ; Martius inBot. Zeitung, 1831. p.449. Richard 
in Arch, de Bot. 1. 11. (1833). — Arace.®, Schott Meletemata, 16.(1832). 
Essential Character. — Flowers unisexual, arranged upon a spadix, within a spathe. 
Perianth wanting. Males : Stamens definite or indefinite, hypogynous, very short ; anthers 
1- 2- or many-celled, ovate, turned outwards. Females : Ovary superior, 1 -celled, very sel- 
dom 3-celled, and many-seeded ; ovules erect, or pendulous, or parietal ; stigma sessile. 
Fruit succulent. Seeds pulpy ; embryo in the axis of fleshy or mealy albumen, straight, 
taper, with a cleft in one side, in which the plumule lies ; {radicle obtuse, usually next the 
hilum, occasionally at the opposite extremity. R. Br.) Albumen sometimes wanting. — 
Herbaceous plants, frequently with a fleshy cormus, or shrubs ; stemless or arborescent, or 
climbing by means of aerial roots. Leaves sheathing at the base, convolute in the bud, 
either with parallel or branching veins ; sometimes compound ! often cordate. Spadix 
generally enclosed in a spathe. 
Affinities. The Arum tribe may be considered the centre of a system 
of organisation, of which the other orders of Spadicosse are rays of unequal 
length. Taking its diagnosis as given above, we shall have it specially known 
by its highly developed spathe ; Typhaceae will be distinguished by their long 
anthers and want of spathe ; Pandanaceae by their arborescent habit and drupa- 
ceous compound fruit; Fluviales and Juncaginaceae by their want of spathe and 
by their return from the spadiceous form of inflorescence ; and Pistiaceae by their 
reduction to the simplest state in which flowering plants can exist. The whole of 
these tribes, taken together, are known by their general tendency to develope 
their flow’ers upon a spadix, by their want of floral envelopes, or by those 
parts not assuming the distinct forms of calyx and corolla, but existing only 
in the state of herbaceous scales. With the exception of Pandanaceae, they 
are all also known by their plumule lying within a cleft of the embryo ; a struc- 
ture found in no other monocotyledonous plants, except Grasses, in which the 
embr}’^o is otherwise widely different. Brown has remarked that in Dracontium 
polyphyllum and foetidum, in which there is no albumen, the plumule consists 
of imbricated scales, and that is sometimes double or even triple. In the for- 
mer of these plants the external scales, in germination, quickly wither away, 
when other internal and larger ones appear, and remain for some time round 
the base of the primordial leaf, before the developement of which no rootlets 
are emitted. Prodr. 334. A similar economy has been noticed by Du Petit 
Thouars, in his genus Ouvirandra in Ahsmacese. The order has been remodelled 
by Schott, upon whose authority I give the genera, &c. 
Geography. Natives of all tropical countries abundantly, but of tempe- 
rate climates rarely, not extending in Europe further north than 64° north 
latitude, in the form of CaUa palustris, which inhabits the deep, muddy, frozen 
marshes of southern Lapland. In cold or temperate climates they are usually 
herbaceous, while in tropical countries they are often arborescent and of con- 
siderable size, frequently clinging to trees by means of their aerial roots, which 
they protmde in abundance. In America, according to Humboldt {Distr. 
G^ogr. 196.), their principal station is on the submontane region between 
1200 and 3600 feet of elevation, where the climate is temperate and the rains 
abundant. In the Andes, Pothos pedatus and P. quinquenervius rise to the 
height of 8400 feet. 
Properties. A principle of acridity generally pervades this tribe, and ex- 
