THUJA. 



288 



THUNBERGIA. 



lemis. (See Piptanthus.) None 

 of the species belonging to this genus 

 will thrive unless they are grown in 

 very rich mould. 



Thistle. — See Carduus. 



Thomasia. — ByttneriacecB. — 

 Pretty little Australian shrubs, for- 

 merly called Lasiopetalum. They 

 should be grown in sandy peat, and 

 kept in a greenhouse. 



Thorn Apple — See Datura and 

 Stramonium. 



Thrift. — Stdtice Armeria, Lin. ; 

 Armeria vulgaris, "Willd. — See Ar- 

 meria. 



Tkrips. — Very small flies, not 

 above a line in length, and which 

 seem rather to leap than to fly away 

 when it is attempted to catch them ; 

 throwing up the lower part of their 

 bodies at the same time, as though 

 they curled themselves up to take a 

 spring. They are very destructive, 

 and attack both leaves and petals, 

 causing both to curl up, and after- 

 wards to turn yellow and drop off. 

 The larvse are nearly as large as the 

 perfect insect, and of a pale yellow ; 

 and the insect itself is first yellowish, 

 bat afterwards becomes black. As 

 soon as the ravages of these little 

 creatures are perceived, the plants 

 they have attacked should be well 

 and frequently syringed, and exposed 

 as much as possible to the free air ; 

 hand-picking in their case being of 

 little avail, from the very small size 

 of the insects and their extraordinary 

 activity. 



Throatwort. — See Trachelium. 



Thuja. — Coniferce. — The Arbor 

 Vitae^ There are two kinds of Arbor 

 Vita? common in British gardens, the 

 American (Thuja occidentalis), and 

 the Chinese (T. orientalis), both 

 having several varieties. The Ame- 

 rican species is an open-growing tree 

 with horizontal branches ; and in 

 America, where it is called the White 

 Cedar, it grows in swamps. The Chi- 



nese Arbor Vitse, on the contrary, is 

 a close-growing tree, with upright 

 branches, and should be grown in a 

 dry soil. Both are quite hardy in 

 the climate of London, and both are 

 propagated by layers and cuttings; the 

 former taking two years to root, and 

 the latter being very difficult to strike. 

 Besides these there are several other 

 species, most of which require a 

 greenhouse or protection during win- 

 ter. The principal of these are 

 Thuja pendula and T. articulata, 

 Desf. ( Callltrisquadrivalvis,Vent.); 

 the latter species, which is a native 

 of Mount Atlas, in Barbary, produ- 

 cing the gum Sandarach, aud being 

 the celebrated Spanish wood Alerce, 

 which is so hard that it is said to re- 

 sist fire, and of which the cathedral 

 of Cordova was built. It is also sup- 

 posed to have been the sandal-wood 

 of the ancients. 



Thunbergia. — Acanthacece.-- The 

 beautiful climbing plants generally 

 known by this name differ very much 

 in the colour of their flowers, though 

 very little in their shape. Some bo- 

 tanists divide them into three genera. 

 T.Hawtayneana, with dark-purplish 

 flowers, they call Meyenia ; and of T. 

 coccinea, with three other nearly- 

 allied species, they have formed the 

 genus Hexacentris ; while they leave 

 T. grandiflora, with dark blue flow- 

 ers, T. fragrans, the flowers of 

 which are white and sweet-scented, 

 T. aurantiaca, with orange flowers, 

 and T. alata, with buff flowers, with 

 its white-flowered variety, in the ge- 

 nus Thunbergia. T. alata, and T. 

 aurantiaca, which is probably only a 

 darker-coloured variety, are the most 

 common of these kinds, and they may 

 be grown either as stove or greenhouse 

 climbers, or as half-hardy annuals. 

 T. alata is a native of the East In- 

 dies, and when treated as either a 

 greenhouse or a stove plant, it is very 

 apt to be covered with the red spider 



