THI 



[ 872 ] 



THR 



is allowed to remain will amply reward 

 the grower, in harvest time, for the 

 apparent sacrifice made. But he will 

 not reap his reward only in this year, 

 for the trees, thus kept unweakened by 

 over-production, will be able to ripen 

 their wood, and deposit their store of 

 sap in their vessels, so absolutely 

 necessary for their fruitfulness next 

 season. 



Thinning is a most necesssary opera- 

 tion with plants as well as with the 

 fruit they bear. The roots of a plant 

 extend in a circle round it, of which 

 the stem is the centre. If the roots of 

 adjoining plants extend within each 

 other's circle, they mutually rob of 

 nutriment, and check each other's 

 growth. Thinning in the seed-bed is 

 generally applied with too timid a hand. 



THISTLE. Ca'rduus. 



THOMA'SIA. (Named after Messrs. 

 Thomas, two brothers, collectors of 

 Swiss plants. Nat. ord., Byttneriads 

 [ByttneriaceseJ. Linn., 5-Pentandria 

 1-Monogynia. Allied to Lasiopetalum.) 



Greenhouse, New Holland, evergreen shrubs. 

 Cuttings of firm, stubby, young side-shoots, in 

 sand, under a bell-glass, in April ; sandy fibry 

 loam and peat, with a little charcoal and broken 

 pots, and pots extra-well drained. Winter 

 temp., 40 to 48 j a sheltered airy place in 

 summer. 

 T. cane'scens (hoary). Purple. June. 1835. 



diffu'sa (straggling). White. April. 1822. 



dumo'sa (bushy). 2. White. May. 1826, 

 folio'sa (leafy). 3. June. 1823. 



glutino'sa (clammy). Red. May. 1842. 



grandiflo'ra (large-flowered). Red. 1840. 



panicula'ta (pamcled). Red. June. 1842. 



pauciflo'ra (few-flowered). Red. June. 1848. 



purpu'rea (purple). 3. Purple. June. 1803. 



quercifo'lia (Oak-leaved). 3. Purple. May. 



1803. 



solana'cea (Potato-like). 3. White. June. 



1803. 



stipula'cea (/or^e-stipuled). 3. Red. 1842. 



triphy'lla (three-leaved). 3. June. 1824. 



THORN-APPLE. Datu'ra. 



THOROUGH-WAX. JBupleu'rum rotun- 

 difo'lium. 



THOUI'NIA. (Named after A. TJwuin, 

 professor of agriculture, <&c., in Paris. 

 Nat. ord., Soapworts [Sapindacese]. 

 Linn., 8-Octandria I-Monoffynia. Allied 

 to Nephelium.) 



Stove evergreen shrub. Cuttings of firm 

 side-shoots, in sand, under a bell-glass, in heat ; 

 sandy fibry loam, and a little peat or leaf- 

 mould. Winter temp.. 50 to 58: summer, 

 fiO to 85. 



T. pinna'ta (Icafleted). 8. White. New Spain. 

 1823. 



THRIFT. Sta'tice. See Edging. 



THRI'NAX. (From thrinax, a fan ; 

 shape of the leaves. Nat. ord., Palms 

 [Palmacese]. Linn., 6-Hexandria 1- 

 Monogynia.} 



Stove Palm. Seeds, in a moist sweet hotbed, 

 in spring ; rich loamy soil. Winter temp., 55 

 to 60 ; summer, 60 to 90. 



T. parviflo'ra (small-flowered). 16. White, 

 green. Jamaica. 1778. 



THRIPS. Thrips Adonidum is one of 

 the worst pests that can gain a footing 

 in our stoves and greenhouses. The 

 larvee and pupes are yellowish-white, 

 and the perfect insect is of a dull deep 

 black, with the point, and sometimes 

 the whole of the abdomen, of a rust 

 colour ; the wings are dirty white ; the 

 horns and legs yellowish, the extremity 

 of the former black. It attacks plants 

 by piercing the under side of the leaves ; 

 and one often sees, at the tip of the 

 tail, a globule of blackish fluid, which 

 it soon deposits, and by innumerable 

 spots of this glutinous matter the pores 

 of the leaves are stopped up, and large 

 portions of the surface become blotched. 

 During March the full-grown larvee and 

 pupee, which are as large as the perfect 

 insect, are found in groups, feeding on 

 the under side of the leaves ; and at 

 this time the recently-hatched but per- 

 fect insect either lies close under the 

 ribs, or roves about in search of a mate 

 (Curtis). Flowers of sulphur have 

 been recommended as destructive of 

 this plague, but we believe that Scotch 

 snuff, applied by means of a dredging 

 box (perhaps Brown's Fumigator would 

 answer), is as effectual an application 

 as any. Prevention, however, is better 

 than cure ; and if the plants are kept 

 healthy by due ventilation, and by 

 moisture both in the air and soil, this 

 insect may be usually banished. 



T. ochraceus infests the ripe fruit of 

 plums, peaches, and nectarines, piercing 

 the stalks and causing their fall, and 

 rendering the fruit disgusting. It was 

 first noticed, and described by Mr. 

 Curtis. It is narrow and linear, of a 

 bright and deep ochreous colour, the 

 eyes are black, the horns appear to be 

 only six -jointed and brownish at the 



