THUJA. 



114 



THUNBERGIA. 



species belonging to this genxis will 

 thrive unless grown in very rich 

 mould. 



Thistle. — See Ca'rduus. 



TH0MA'siA.-^?/<<ne7-/«cc«?.-Pret- 

 ty little Australian shrubs, fonnerly 

 called Lasiopetalum. They should 

 be grown in sandy jjeat, and kept in 

 a greenhouse. 



Thorn Apple. — SeeDAiu^RA and 

 Stramo'xiuii. 



Thrift. — Stdiice Armeria Lin. ; 

 Armeria mdgaris WOld. — See Ar- 



ME^RIA. 



Theips. — 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- 

 vv'ards to turn yellow and drop ofi". 

 The larvffi are nearly as large as the 

 perfect insect, and of a pale yellow ; 

 and the insect itself is first yellow- 

 ish, but afterwards becomes black. 

 As soon as the ravages of these 

 little creatures are perceived, the 

 plants they have attacked should be 

 vrell 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 Trache'- 



LIUM. 



Thu'ja. — ConifercB. — The Arbor 

 Vitse. — There are two kinds of Arbor 

 Vitge common in British gardens, the 

 American {Thuja occidenUdis), and 

 the Chinese {T. oriental is), 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 Chinese Arbor Vita?, on the 

 contrary, is a close-growing tree, 

 Avith upright branches, and should 

 be grown in a dry soil. Both ai'e 

 quite hardy in the climate of Lon- 

 don, 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 

 Tliitja 'pendida and T. articulata 

 Desf. {CdUitris quadrivdlvis Vent.); 

 the latter species, which is a native 

 of Mount Atlas, in Barbary, pro- 

 ducing the gum Sandarach, and 

 being the celebrated Spanish wood 

 Alerce, which is so hard that it is 

 said to resist fire, and of which the 

 cathedral of Cordova was built. It 

 is also supposed to have been the 

 sandal-wood of the ancients. 



Thunbe'rgia. — Acanthdcece. — 

 The beautiful climbing plants gene- 

 rally known by this name difl'er very 

 much in the colour of their flowers, 

 though very little in their shape. 

 Some botanists divide them into 

 three genera. T. Hawtaynedna, 

 with dark - purplish flowers, they 

 call Meyenia ; and of T. coccinea, 

 with three other nearly-allied spe- 

 cies, they have formed the genus 

 Hexacentris ; while they leave T. 

 firandifldra, with dark-blue flowers, 

 T. frdgrans, the flowers of which 

 are white and sweet-scented, T. 

 aurantiaca, with orange flowers, 

 and T. aldta, with bufi" flowers, 

 ■ndth its white-flowered variety, in 

 the genus Thunbergia. T. aldta 

 and T. aurantiaca, which is proba- 

 bly 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. aldta is a 

 native of the East Indies, and when 



