DIOPTASK. 



niospYiios. 



S'fl 



gfcauU of UM Ueocan. At an elevation of 3000 feet above the level of 

 UM *. 19' SS' N. Ut, 71' 40' E. long. 



" This uwect affect* cluuuis or ravine* in the lofty traoOi which 

 eneirele UM mountain in U-IU. In various places, where the sun- 

 beam* occasionally pierce the wood* and fall ti|>on isolated or salient 

 rock* in UM above localities, they are *een in myriads, either poising 

 UMOuclve* in UM ray*, or reposing on the ipot* on which the 

 ray* fall." 



All UM known specie* are from the tropical part* of Uie Old World. 



( \Vwtw.xid, Trmuactiotu of Limnaan Socitty.) 



1 Mi "1TASK, a Silicate of Copper. [Corncm] 



I Hi MUTE, a rock consisting of Albite and Hornblende, also called 



lilOSCOIlEA, a genus of Plant* which furnish the tropical 

 MolonU called Yams. It is the type of the natural order Diotco- 

 rrarrtr. The genus consist* of perennial fleshy-rooted or tuberous 

 dioecious plants, with annual twining stems, broad alternate leaves 

 having a somewhat netted arrangement of their veins, and loose 

 cluster* of small green flowers. The corolla and the calyx taken 

 together consist of 6 small equal segment*, which, in the females, 

 stand upon the top of the ovary. The male flowers have 6 stamens ; 

 the female* 3 styles. The seed-vessel is a thin compressed 3-wiugod 

 capsule, containing one or two membranous seed*. 



The be*t account of the species is that of Dr. Roxburgh, who 

 cultivated seventeen sorts in the Botanic Garden, Calcutta ; others 

 are known to botanists, but far from perfectly. 



D. alata, the common West India Yam. It is a native of the West 

 Indies, but i* met with in the East Indies also, but only in a culti- 

 vated state. A figure of it is given in Rheede's ' Hortus Malabaricus,' 

 vol. vii. t 38, under the name of Katsji-kelengu. Its tubers ore 

 oblong, brown externally, white internally, and often of great size, 

 weighing sometimes as much as SOlbs.; they perish' after the first 

 year, if left in the ground, having first produced the young ones that 

 are to replace them. "Besides the tubers the proper roots of all 

 these plants are fibrous, springing from and chiefly about the union 

 of the stems with the tubers, and spreading in every direction." The 

 terns are furnished with four crested leafy wings, and spread to a 

 great extenV twining round trees and bushes ; they often bear prickles 

 near the ground. The first leaves that appear on the stem are 

 alternate, the succeeding are opposite, seated on long stalks, deeply 

 heart-shaped at the base, sharp-pointed, smooth, with from five to 

 even rib*. The flowers are small and green, and appear in compound 

 panicle*. The remainder of the species are very similar to this in 

 general characters ; a few short notes will sufficiently indicate their 

 differences. 



It. globota, cultivated in Bengal under the name of Choo-Puree- 

 Aloo, is most esteemed of the Indian Yams. Its flowers are highly 

 fragrant ; the tubers are white internally ; the leaves arrow-headed. 



1>. mMla, the Guranya-Aloo, is another Indian sort with large 

 tubers stained with red immediately below the cuticle ; it is much 

 esteemed ; it* tubers are sometimes three feet long ; its flowers are 

 fragrant 



/>. jwrpvrm, called Lal-Guranya-Aloo in Bengal. The tubers are 

 permanently stained purple throughout 



At Mnlf~* is cultivated another purple-rooted sort, the 1). a/ro- 

 j,urjmrea, whole tubers an large and irregular, and grow so near 

 Uie surface of the ground as to appear in dry weather through the 

 cracks that they make in the soil by raising the earth over them. 



Other eatable sorts are numerous, but are leas valuable, s 

 therefore not cultivated. In Otaheite the D. bulbifrra, which bears 

 small fleshy angular tuber* along the item in the axils of the leaves, 

 is the favourite species. 



It is not a little remarkable that while so many species are nutri 

 tious in this genus, some should be highly dangerous ; but such 

 is unquestionably the fact 1). Dtntonum and /'. Iriphylla, both 

 teroate-leaved species, have very nauseous and dangerous tubers. 



niOHCOKEA'CE.*:, Yarn*, the Yam Tribe, a natural order of 

 Plant* belonging to the class Dictyogena. They are particularly 

 dutinguisbedbv the following character* : 



Flowers diceciou* ; calyx and corolla superior ; stamens 6 ; ovary 

 Swelled, with 1 or 2-*eeded cells; style deeply trifid; fruit leafv 

 compressed, occasionally succulent; embryo small, near the hilum, in 

 a large cavity of cartilaginous albumen. The affinities of this order 

 are with Bmilatta and Aritiolocliiacnr. It contains 6 genera and 100 

 specie*. 



All the species are twining shrubs, with alternate or spuriously 

 opposite leave*. They consist, with the exception of Tamtu, lilac! 

 Bryony, of tropical plant*, or at leait of such as require a mile 

 frosUees climate. Home of them produce eatable farinaceous tubers, 

 or yams, as the various specie* of Diotcona and Tettudinaria ; bu 

 there i* a dangerous acrid principle prevalent among them, which 

 render* UM order upon the whole suspicious. It exist* in a perceptible 

 degne in Tamtu, and i* still more manifest in the 3-leaved Dioicorta. 

 [TAMCI; Tnm-niKAMA ; DICMCOBCA; KAJAHIA.] 



IllOSMA, a genus of Kutaceous Shrub* inhabiting Uie Cape o 

 Good Hope. They have alternate simple leaves, strongly market 

 with dot* of transparent oil, and diffusing a powerful odour when 

 bruised. Some of the species are offensive to the European taste, as 



1, a shoot of Rqjania cordala ; 2, a mule flower ; 3, a female flower ; 4, a 

 portion of a ripe fruit with the seed exposed i 5, section of the seed. 



the Buckus with which the Hottentots perfume themselves, and which 

 ore chiefly yielded by D. crenata and D. ttrratifolia. The flowers of 

 most are white ; those of a few are red. By most modern botanists 

 the old genus Diotma, is broken up into eight, namely, Atlenamlra, 

 CoUonema, Jtiotma proper, Euduxtit, Aemadenia, Baryotma, to which 

 the Buckus belong, Agalhotma, and Afacrvttylit. 



The following are the best known species of the old genus 

 Diotma : 



D. ttrratifolia has linear lanceolate leaves, acuminate, serrulated, 

 smooth, glandular at the edges, and 3-nerved. The flowers are lateral, 

 white, upon short axillary brocteate peduncles. This species is an 

 erect shrub, smooth in every part, and growing a foot or so 

 high ; branches tapering, purplish, long, lax ; branchletg somewhat 

 whorled, ternate or scattered, angular, purple, twiggy, incurved, loose. 

 Leaves alternate on short stalks, ovate-oblong, blunt, flat, smooth, 

 deep green above, paler beneath, dotted with sunken gland 

 midrib somewhat keeled, the margin scolloped, glandular-dotted, and 

 ahining. Flowers solitary, white, middle sized. Peduncles filiform, 

 shorter than the leaves. 



J). crenulata is an upright shrub between two and three feet high, 

 with twiggy branches of a brownish purple tinge. The leaves are 

 decussate, spreading, about an inch long, oval-lanceolate, on very short 

 petioles, very obtuse, delicately and minutely crenated, quite glabrous, 

 rigid and quite smooth above ; the peduncles about as long as the 

 leaf, axillary, and terminal, chiefly from the superior leaves. 



D. crenata (Linn.), D. terratifolia (Vent), and D. crcnu'nin \irld 

 leaves which at the Cape of Uood Hope are termed Buchu, or Hue, ,., 

 nn,l which are sometime* used alone, but more frequently mixed. 

 \Vlii-n bruised they emit a strong peculiar odour resembling rosemary 

 or rue. The taste i* aromatic, but not bitter or disagreeable. 



t de Oassecourt analysed the leaves, and found no alkaloid, 

 but 6'65 of volatile oil ; 21 '17 extractive; 2'15 resin; 63 lignin ; Tin 

 chlorophylle. brandes considers the extractive to bo peculiar, and 

 terms it Diostnin, analogous to Cathartin. The volatile oil :m,l th,- 

 extractive appear to be the active ingredient: Th.-y arc usually 

 odiniiiiHUTcd in the form of infusion. [llrriir, in A UTS \M> 

 Bfl. lnv.| 



I MI KSPYKOS (from fcot and in/pit, which may be translated ' celes- 

 tial food'), a genus of Plants belonging to the natural order Kbtnatnr. 

 They all form large trees, with alternate thick often coriaceous leaves. 

 The flowers are usually single and axillary, the male and female flowers 

 separate or united. Calyx and corolla 4-cleft, rarely 5-clH't. StainiinL 

 often 8, but varying in different species. Germ superior, often 8-celled ; 

 cells 1 -seeded ; attachment superior. Styles 8 or 4, rarely S, or ; 

 variously divided. I'.nry IP. in 1 to 12 heeded, often 8-fleedod. Ktulirx,) 

 invenw, and furnished with allniiii' j ii. Mali- tl"u,-r l'i ",|u>>ntly with 

 twin anthers. The species are found chiefly in the tropical parts both 

 of Asia and America, as in the Malayan Archipelago and Peninsula, 



