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[ORCH 



ORBEA. A name given by Haworth to 

 some of the species of Stapelia, but not 

 generally adopted. 



ORBICULAR. Perfectly circular ; as the 

 leaf of Cotyledon orbiculare. 



ORBICULT7S. The fleshy ring formed 

 by the stamens of Stapelia. The circular 

 bodies found in the cup of a Nidularia. 



ORBIG:NTA. Two Bolivian palms, one 

 ■with a tall stem and the other dwarf, and 

 perhaps a third little-known species from 

 Brazil, are comprehended in this genus, 

 which belongs to the same section of palms 

 as the cocoanut. The leaves are pinnate, 

 and the flower-spikes simply branched and 

 enclosed in double spathes, the inner of 

 which is completely closed while young. 

 Some spikes bear male flowers only, and 

 others both female and perfect ones. The 

 fruit has a fibrous husk enclosing a hard 

 bony stone. O. phalerata, the Cusi or Cu- 

 sich palm of Bolivia, is a tall-stemmed 

 plant with large rather erect pinnate 

 leaves, which the Indians use for building 

 and thatching their huts, and for weaving 

 into hats and mats. They also obtain a 

 fatty oil from the seeds, and use it for 

 anointing their hair. Each fruit contains 

 from three to seven seeds, but the stone 

 in which they are enclosed is so hard that 

 they are extracted with difficulty. [A. S.] 



ORBILLA. Such a shield as is found in 

 lichens of the genus Usnea. 



ORCANETTE. (Fr.1 Alkanna tinctoria ; 

 also Onosma. — JATJNE. Onosma echi- 

 oides. 



ORCHELLA-WEED. The name of seve- 

 ral species of Roccella, a genus of lichens 

 I celebrated for their valuable properties as 

 1 dye-weeds. These vary much in value ac- 

 cording to their species, or rather varieties 

 (for authors have most needlessly multi- 

 I plied species), and the country in which 

 they grow, that from Angola being the 

 most valuable and at the same time most 

 economical, a matter of much consequence 

 when the high price is takeninto considera- 

 tion. Some specimens were exhibited 

 from Ceylon in 1851 in the Great Exhibition, 

 whose estimated value was 380L per ton. 

 Two kinds of orsellic acid and erythric acid 

 are the chemical substances on which their 

 dyeing properties depend. Orchella-weed 

 is found on the maritime rocks of hot or 

 warm temperate regions. In Great Britain 

 it is confined to the south. In India it is 

 found occasionally on the trunks of the 

 Mango, and a similar habitat produces a 

 species in Algiers. The flat and cylindrical | 

 forms run so much into each other that 

 the distinction of species is a matter of 

 some difficulty. pi. J. B.] 



ORCHIDIUil. Calypso. 



ORCHIDOFUXK1A. Cryptarrhena. 



ORCHIDACEiE. (Orchidece, Orchids^ A 

 natural order of Endogens, the type of the 

 orchidal alliance, in which they are distin- 

 guished by their irregular gynandrous 



I flowers and parietal placentae. They are 

 perennial herbaceous plants or shrubs, in 

 temperate countries assuming a terrestrial 

 habit, in warmer latitudes growing on trees 

 (epiphytes), or fixing themselves to stones. 

 Their roots are fibrous and fasciculated, 

 or fleshy,or tuber-like and filled with starch 

 or horny nodules of bassorin. Their stems 

 are sometimes annual, sometimes peren- 

 nial and woody, and sometimes pseudo- 

 bulbous ; their leaves are flat, terete or 

 equitant, generally sheathing; and their 

 i flowers are irregular, extremely variable in 

 form, and often most gratefully fragrant. 

 The flowers consist of three sepals, equal 

 at the base, or variously extended there; 

 three petals placed between the sepals, the 

 lateral usually similar to the dorsal sepal; 

 the third, called the lip or labellum, usually 

 larger than the petals, and quite unlike 

 them in form, horned or furnished with 

 various appendages, occasionally moveable 

 I as if spontaneously, now and then con- 

 i tracted so as to form separate parts, of 

 which the lowest is called the hypochil, 

 i the highest the epichil, and the middle one 

 I the mesochil. The stamens and style are 

 consolidated into a central body called the 

 column; and of the three stamens thecen- 

 i tral only is perfect, except mCypripedium, 

 where the central is abortive and the two 

 lateral perfect. The pollen is powdery, or 

 collected into grains, or adhering in wedges 

 tied together by an elastic material, or con- | 

 solidated into masses of a waxy texture j 

 and fixed number, the masses either free ■ 

 or adhering by a caudicle to a gland be- 

 longing to the apex (or rostellum) of the [ 

 stigmas, which latter are usually confluent 

 in a hollow mucous disk. The ovary is 

 adherent, one-celled; the capsule very rare- 

 ly fleshy, indehiscent and pod-shaped, usu- 

 ally breaking up into six dry woody rigid 

 valves with horizontal cells, of which three 

 only bear the innumerable very minute 

 seeds which have a loose netted skin. 



The order owes its chief peculiarities to 

 the consolidation of stamens and pistil 

 into one common mass, called the column ; 

 to the suppression of all the anthers, ex- 

 cept one in the mass of the order, or two 

 in Cypripedece ; to the peculiar condition 

 of its pollen, and the anther which contains 

 it; and to the very general development 

 of one of the inner leaves of the perianth 

 or petals in an excessive degree, or in an 

 unusual form. The irregularity of the la- 

 bellum, however, disappears in such genera 

 as Tlielymitra, Paxtonia, Hexisea, and 

 others ; but irregularity is predominant, 

 and the flowers assume such unusual 

 figures that there is scarcely a common 

 reptile or insect to which some of them 

 have not been likened. 



The irritability of the labellum is otfe of 

 the curious peculiarities of these plants. 

 This is seen in different species of Pterosty- 

 lis, Megaclinium, and Podophyllum. In 

 Caleananigrita the column isaboat-shaped 

 box resembling a lower lip ; the labellum 

 forms a lid that exactly fits it, and is hinged 

 on a claw which reaches the middle of the 

 column : when the flower opens, the label- 



