isot] 



&f)£ CrcaSurg at 2Sntanp. 



632 



I. longiflora, a native of the West Indies, is 

 a most venomous plant, producing danger- 

 ous cathartic symptoms. It proves fatal 

 to horses that eat it. Others of the species 

 are natives of Australia. [M. T. MJ 



ISOTROPIS. The generic name of a few 

 erect or decumbent leguminous herbs, 

 found in South-west Australia. They most- 

 ly have slender rush-like stems six inches 

 to a foot high, with alternate spathulate 

 leaves about an Inch long, usually bilobed 

 at the apex ; and solitary and long-stalked 

 or racemed pea-flowers, the standard yel- 

 low with purple lines, and the keel and 

 wings purple. The flowers are much like 

 those of Chorozema, so often seen in green- 

 houses, and have a deeply four-cleft calyx, 

 and orbicular bilobed standard, free sta- 

 mens, and an oblong membranaceous 

 pod. [A. A. B.] 



ISOTYPUS. A genus of South American 

 two-lipped composites. The present name 

 supersedes Caloseris : which see. 



ISPRUK. An Indian powder made from 

 a species of Delphinium. 



ISTHMIA. One of the finest genera of 

 Diatomacece, distinguished by its trapezoid 

 or rhomboid articulations, which are com- 

 pressed and cellular, marked with a trans- 

 verse zone, composed of smaller cells, and 

 supported at one corner by a short stem. 

 We have two native species which form 

 most interesting objects for the micro- 

 scope, and are very instructive as exhibit- 

 ing, most distinctly, the peculiar mode in 

 which cell-division takes place in these 

 algas. The new frustules are either at- 

 tached alternately as in Diatoma, or united 

 to each other by means of a very short 

 blunt stem, springing from one corner and 

 fixed to different points of the older frus- 

 tules. [M. J. B.] 



ITAKA WOOD. A cabinet wood pro- 

 duced from Machcerium Schomburgkii. 



ITEA virginica, the only representative 

 of this genus of Escalloniacece, is a North 

 American shrub, with clusters of white 

 flowers, which open in summer. The calyx 

 is bell-shaped ; petals five, lance-shaped ; 

 stamens five, attached with the petals to tlie 

 calyx; ovary with two compartments; 

 fruit capsular, compressed. This shrub is 

 frequently cultivated in shrubberies in 

 this country, and derives its name from 

 the Greek name for the willow, which it 

 resembles in its mode of growth. [M. T. M.] 



• ITOUBOU. Ipnidium Ituba. 



IVA. The generic name of a few rank- 

 growing annual or biennial weeds of the 

 composite family, found in marshy or 

 maritime places in North America. The 

 stems have nettle or willow-like leaves, 

 opposite below, and alternate above ; and 

 the greenish-white flower-heads, some- 

 what like those of Artemisia, are arranged 

 in racemes, or placed singly in the axils of 

 the upper leaves or bracts. The florets are 

 all tubular, inconspicuous. [A. A. B.J 



IVETTE. (Fr.) Ajuga Chamcepitys. — 

 MUSQUEE. Ajnga Iva. 

 I VRAIE. (Fr.) Lolium temulentum. 



IVORY, VEGETABLE. The hard albu- 

 men of the nuts of Phytelephas macrocarpa. 



IVY. Hedera Helix. — , AMERICAN. 

 Ampelopsis hederavea. — , GERMAN. A 

 garden name for Senerio vukanoides. — , 

 I GROUND. Xepeta Glechoma. — , POI- 

 SON. Bhus Toxicodendron. 



IVYWORTS. Lindley's name for the 



Araliacece. 



IXERBA. A genus of Brexiacece, re- 

 presented by a single species, I. brexioides, 

 which is an elegant evergreen tree of New 

 Zealand, growing to the height of twenty 

 feet, and having lance-shaped leaves, and 

 terminal panicles of few large white flow- 

 ers. The leaves are glossy, leathery, and 

 toothed ; and the flowers consist of five 

 calyx leaves, five petals, five stamens, and 

 a lobed disk surrounding a five-celled 

 ovary. The name Ixerba is an anagram of 

 Brcxia. [A. A. B.] 



IX I A. A genus of beautiful Cape irida- 

 ceous bulb-tuberous plants, with narrow 

 ensate leaves, and slender simple or 

 slightly branched stems bearing spikes of 

 large showy flowers, various in colour, and 

 exceedinglyattractive when fully expanded 

 by sunshine. These flowers have a salver- 

 shaped perianth, with a slender tube, and 

 six-parted spreading equal limb, three sta- 

 mens inserted in the throat, with filiform 

 filaments and versatile anthers, and a 

 three-celled ovary with numerous ovules, 

 terminating in a filiform style, and three 

 narrow linear conduplicate recurved stig- 

 mas, i". viridiflora, which has large sea- 

 green flowers with black markings at the 

 base of the segments, is a very singular- 

 looking as well as beautiful plant. There 

 are a great many species, and some garden 

 varieties. [T. M.] 



IXIANTHES retzioides is an erect South 

 African shrub, with lanceolate whorled 

 leaves, and very viscid flowers, growing 

 singly or two or three together on axillary 

 peduncles. It forms a genus of Scroplmla- 

 riacece of the tribe Chelonece, distinguished 

 by a two-lipped calyx, by the corolla which 

 has a short broad tube, a short erect upper 

 lip, and a longer three-lobed spreading 

 lower lip, and by the stamens, of which two 

 only bear anthers. 



IXIANTHUS. A genus of the gentian 

 family, represented by a perennial plant, 

 native of Teneriffe, with sticky leaves and 

 yellow flowers. The calyx is provided with 

 exterior triangular bracts ; the corolla 

 is wheel-shaped, with a four-cleft limb ; 

 there are four stamens ; and the capsule 

 is partly two-celled, two-valved. [M. T. M.] 



IXIOLiENA. A few annual Australian 

 herbs compose this genus,which belongs to 

 the same group of the composite family 

 as the everlastings. They have glutinous 

 smooth or woolly stems, six inches to a 



