1159 



SHjc Crea^uri? at botany. 



[teag 



TRACHEA. Spiral vessels ; air-tubes, 

 containing a spiral thread of considerable 

 toughness aud elasticity, 



TRAOHELANTHUS. A genus of Bora- 

 ginacece, founded on Solenanthus cerin- 

 thoides a native of Northern Persia. It 

 has the corolla of Cerinthe, being tubular, 

 with a flve-lobed lirab about one third the 

 depth of the whole , the lobes have two 

 bulges at the base ; the scales in the throat 

 are lanceolate from a triangular base ; the 

 colour is red, margined with yellow. The 

 fruit is similar to that of Cynoglossum, a 

 smooth glaucous plant, with the stem co- 

 rymbose paniculately branched at the top, 

 the leaves rigid and leathery, with small 

 tubercles beneath. [J. T. S.] 



TRACHELIUM. A genus of Campana- 

 lacece, containing a few species of peren- 

 nial plants, with alternate ovate-acute 

 deeply serrated leaves, and violet blossoms 

 in a many-flowered terminal corymb. The 

 calyx has five subulate divisions ; the corol- 

 la has a long slender tube, and a spread- 

 ing flve-lobed limb; the filaments of the 

 stamens are filiform throughout their 

 length, and free at their base ; and the apex 

 of the exserted style is thickened, and 

 densely covered with hairs. The species are 

 found in the Mediterranean region. [W. C] 



TRACHYDITJM. A genus of Umbelliferce 

 founded on a single species from the moun- 

 tains of Northern India. It is an annual 

 or biennial, sending out from the crown of 

 the root, both leaves, and numerous casspi- 

 tose simple stems. The leaves are petio- 

 late and tripinnatisect, the opposite divi- 

 sions being bipinnatisect, and the lobes 

 lanceolate acute. The segments of the invo- 

 lucre are similar to but smaller than the 

 ordinary leaves, and those of the involu- 

 cels are more or less united and membra- 

 naceous. The calyx has five small Seeth ; 

 the petals are lanceolate, with incurved 

 acuminate apices ; the fruit is compressed 

 at the side ; and the carpels have five muri- 

 cated ribs, the furrows with a single vitta 

 in each, while the commissure has two. 

 The carpophore is divided. [W. C] 



TRACHYLOBIUM. A genus of legu- 

 minous plants very closely allied to and 

 by some botauists combined with ffyme- 

 nrea. The principal distinctions between 

 the two genera consists in the petals of 

 Trachylobium being only three in number, 

 nearly equal and long-stalked, the ovary- 

 being elevated on a stalk and bearded with 

 hairs, and the pods covered with wart-like 

 excrescences ; while Hymencea has five 

 stalkless unequal petals, a stalkless smooth 

 ovary, and a pod without warts. The spe- 

 cies are all large trees, bearing panicles 

 of white flowers, and having leaves com- 

 posed of a pair of leaflets. They are natives 

 of Brazil and Madagascar. 



T. Martianum is, according to Martius, 

 one of the trees from which the resin 

 known a3 Brazilian Copal is obtained ; but 

 it is doubtful whether any of this kind of 

 Copal comes to this country, our principal 



supply of that article being derived from 

 Eastern and Western Africa. [A- S.] 



TRACHYMENE. A genus of orthosperm- 

 ous Umbelliferce, containing several spe- 

 cies of herbs or undershrubs, with com- 

 pound many-rayed umbels. The calyx-tube 

 is compressed, and the limb five-toothed; 

 the petals are elliptic and entire, the style 

 is divergent ; the tubereulated fruit is 

 compressed and contracted at the sides, 

 separating into two semi-ovate gibbous 

 carpels; and the carpophore is entire. The 

 genus has been divided by Decandolle into 

 two sections— Platymene, including the 

 herbaceous species, with compressed stem 

 and small divided leaves ; and Bendromeue, 

 comprising the shrubby species with en- 

 tire leaves. [W C] 



TRADESCANTIA. A genus of lily-like 

 plants belonging to the Commelynacece, 

 well marked by their three sepals, three 

 petals, three-celled capsule, and filaments 

 clothed with jointed hairs. T.virginicais 

 the Common Spiderwort of gardens, a 

 pretty plant twelve to eighteen inches 

 high, with numerous branched jointed 

 succulent stems, linear-lanceolate glossy 

 leaves, and dense umbels of flowers con- j 

 spicuous by their three spreading bright- 

 blue petals. Varieties are also cultivated 

 with purple white and double flowers. T 

 rosea from Carolina is like the preceding, i 

 but smaller and more delicate. T. discolor j 

 is so called from the colour of its leaves, I 

 which are green above, purple below, the ! 

 flowers, which are white, issue from a j 

 purple single-leaved spathe. This is a hot- j 

 house plant. Other species are cultivated, 

 all more or less resembling the above I 

 French : EphemSrine. [C. A. J.] 



TRAGACANTH. A kind of gum obtained 

 from Astragalus verus, A. cretieus, A. aris- 

 tatus, A. gummifer, and A. strobiliferus. — , 

 SENEGAL. The produce of Sterculia Trd- 

 gacantha. 



TRAGANTHTTS. The name of a genus 

 of Eiiphorbtacece, comprising certain tro- 

 pical American herbaceous plants, the 

 flowers of which are monoecious, arranged 

 in axillary spikes. The male flowers have 

 a four-parted calyx, enclosing four sta- 

 mens ; and the females have also a small 

 four-parted calyx, girt at the base by large 

 overlapping scales arranged in four rows, 

 a hairy three-celled ovary, and six curved 

 styles. The fruit consists of three carpels, 

 which separate one from the other, each 

 bearing the two persistent styles at the 

 summit. In the centre, between the car- 

 pels, is a winged column, from which the 

 former separate when ripe. [M. T. M.] 



TRAGIA. A genus named in honour of 

 Tragus, an ancient German botanist, who, 

 according to the fashion of the times, as- 

 sumed a classical title, his true name hav- 

 ing been Hieronymus Bock. The genus is 

 included among the Euphorbiacece, and con- 

 sists of herbs or undershrubs, widely dis- 

 tributed in the subtropical regions of the 

 Old and New Worlds. Some of them are of 



