pecies -with what are called terete (i.e. 

 almost cylindrical) leaves. The most re- 

 markable of these is 0. Sprucei, found by 

 Mr. Spruce on the Rio Negro in Brazil, 

 where the natives call it Rabo de Satu or 

 Armadillo's Tail, in allusion to these terete 

 leaves, which are between two and three 

 feet Ions: and nearly an inch thick, like the 

 tail of some animaL 



O. Lanceanum of Surinam, is perhaps 

 the most beautiful species known, having 

 its sepals and petals richly mottled with 

 brown upon a greenish ground, and its lip 

 rose-coloured and deep violet. It is also 



Oncidiuui bicallosuui. 



remarkable for the rich vanilla-like 

 fragrance of its flowers. The tubercular 

 development at the base of the lip is 



; shown in the accompanying figure of 0. 



\ bicallosum. [A. S.] 



] ONCOBA. A genus of Flacourtiacece 



confined to Nubia and tropical Africa, and 



i consisting of spiny trees with alternate 



i oblong and serrated leaves, white race- 



! mose flowers, and a leathery berry the 



pulp of which is sweet and eaten in Nubia. 



i The flowers are hermaphrodite ; the calyx 



i five-cleft and deciduous ; the corolla has 



i five petals: the style is simple, and the 



fruit encloses numerous seeds. [B. S.] 



ONCOSPERMA. The two species of 

 Oncosperrna, a genus of Palms, are placed 

 by some botanists in Areca. They are 

 lofty elegant palms, witli slender spiny I 

 trunks marked with circular scars, termi- i 

 nal pinnate leaves with very spiny sheath- 

 ing footstalks, and pendulous flower- 

 spikes springing from below the leaves ', 

 and enclosed in double spathes. The j 

 flowers are unisexual and usually in threes, I 

 one female between two males upon the I 

 lower part, and in pairs higher up ; in 

 structure they resemble those of Areca, 

 except that the males uniformly have six l 

 stamens with short stout free filaments 

 and arrow-shaped anthers ; and the three , 

 stigmas of the females closely connive. 

 The small round one-seeded fruits bearing 

 the remains of the stigma on one side have 

 a granular (not fibrous) flesh enveloping a 

 thin shell, which closely adheres to the 

 seed. 



0. ftlamentosa, the Nibung or Nibong of 



the Malays, is a very elegant palm found 

 growing in masses in swampy places upon 

 the coasts of Malacca, Sumatra, Borneo, 

 and the islands of the Indian Archipelago. 

 It attains a height of forty or fifty feet, 

 and has leaves ten or twelve feet in length, 

 1 with very numerous narrow drooping 

 leaflets about two feet long. In Borneo 

 the delicate white heart of unexpanded 

 leaves, called the cabbage, is highly es- 

 teemed as a vegetable. The unsplit trunks 

 are used for house-building, for posts, &c, 

 and the hardest part of the split trunks for 

 rafters, flooring, &c. [A. S.j 



ONCOSPORUM. A genus of South-west 

 Australian Pittosporacece, having a calyx 

 of five small leaves, a corolla with five 

 petals, five stamens alternate with the 

 petals, and a short filiform style with a 

 simple stigma. These are succeeded by a 

 membranaceous two-celled seed-vessel, 

 each cell containing from six to ten seeds. 

 It consists of climbing shrubs with alter- 

 nate leaves, and white flowers occasionally 

 striped with purple. [R. H.] 



ONE-BERRY. Paris quadrifolia. 



ONE-BLADE. Convallaria Mfolia. 



ONE-SIDED. Having all theparts turned 

 one way, in consequence of a twist in their 

 stalks. 



ONION. Allium Cepa. — , BARBADOS. 

 Ornithogalum scilloides. — , BOG. Os- 

 mundaregalis. —.POTATO. A variety of 

 Allium Cepa. — , SEA. Urginea Scilku 

 — , TREE. Allium proliferum. — , WELSH. 

 Allium fistulosum. 



ONOBROMA. A name given by De Can- 

 dolle to some Eastern species of Carthamus 

 separated from the rest of the genus on 

 account of the outer florets being neuter 

 without a pappus, whilst the hermaphro- 

 dite central ones have a pappus of linear 

 chaff-like bristles. They are thistle-like 

 plants, with yellow flowers. 



ONOBRYCHIS. A handsome genus of 

 Leguminosce of the tribe Papilionacece, 

 which may be distinguished by its pinnate 

 leaves without tendrils, its spicate flowers, 

 and its wrinkled one-seeded legume or pod. 

 Our only British species is O. sativa, the 

 Common Sainfoin, which occurs not unfre- 

 yuently on English downs where the sub- 

 stratum is calcareous ; it is said, however, 

 not to be met with in Scotland or Ireland. 



Sainfoin has been much cultivated as a 

 shifting fodder crop, especially on the 

 oilite soils, in which its deeply-penetrating 

 roots, by bringing up organic matter from 

 below, act most beneficially in the forma- 

 tion of a thicker crust of soil. This crop 

 was formerly capable of holding on to the 

 soil for as long as eight years, but latterly 

 it has become so mixed with burnet (Pote- 

 riuvi Sanguisorba) as to be very materially 

 injured as a crop, the burnet growing so 

 much faster than the Sainfoin, that the 

 land is taken possession of by the former 

 to the prejudice of the latter. The mix- 

 ture takes place in the seed, more especially 



