AKD GENERAL HORTICULTURE. 



453 



The genus Tril- 



THO 



and mottled with brown. They require the 

 same culture as the Caladium. Syn. Pytho- 

 nium. 



Thorn. A common name for various species 

 of Acacia, CratoBgus, etc. 



Thorn. American Black or Pear. Cratoegus 

 tomentosa. 

 Christ's. Paliurus aculeatus and Ziziphus Spina- 



Christi. 

 Oarland. Paliuriis aculeatus. 

 Goat's. Astragalus Tragacantha. 

 Jerusalem. Parkiyisojiia aculeata. 

 Sea Buck, or Willow. Hippophce, rhamnoides. 

 Wait-a-bit. Uncaria procumbens. 



Thorn Apple. See Datura. 



Thorough-'wax. Buplerum rotundifolium. 



Thorough-wort. Eupatorium perfoliatum. 



Thoui'nia. Named in honor of Andre Thouin, 

 Professor of Agriculture, at Paris, 1747-1824;. 

 Nat. Ord. Sapindaceae. 



A genus of shrubby plants, sometimes climb- 

 ing, natives of tropical America. T. pinnata, 

 the only species introduced, is cultivated in 

 the stove-house, and is an erect-growing 

 plant with white flowers, disposed in terminal 

 panicles. It is increased by cuttings of the 

 ripened wood, and was introduced from St. 

 Domingo in 1823. 



Three-leaved Night-shade. 



Hum. 



Three-seeded Mercury. Acalypha Virginica. 



Three-thorned Acacia. The Honey Locust. 

 Gleditschia triacanthos. 



Thrift. See Armeria vulgaris. 



Thri'nax. From thrinax, a fan ; the shape of the 

 leaves. Nat. Ord. Palmacece. 



A genus of very beautiful West Indian Palms, 

 commonly called, in Jamaica, Thatch Palms, 

 from their leaves being used for thatching. 

 One of the species, T. argentea, the Silver 

 Thatch Palm, furnishes the leaves which, cut 

 before they expand, are used in the manufact- 

 ure of Palm-leaf hats or chip hats. This is a 

 beautiful and ornamental species, and is a 

 great favorite in all collections of greeu-house 

 Paims. T. Barbadensis, T. radiuta (syn. T. 

 elegans), T. elegantissitna and T. graminea, are 

 all elegant, neat-growing Fan Palms, and of 

 easy management. They were first introduced 

 in 1800, and are increased by imported seeds. 



Throat-wort. See Trachelium. Applied also to 

 Campanula Cen)icaria and Digitalis purpurea. 



Thuja. The adopted spelling now is Thuya, 

 which see. 



Thunbe'rgia. Named in honor of Charles P. 

 Thunberg, a celebrated botanist and traveler. 

 Nat. Ord. Acanthacece. 



A genus of very handsome, climbing plants. 

 Some of the species, such as T. alata, T. alba, 

 T. auraniiaca, and the varieties of the same, 

 may be treated as half-hardy annuals. They 

 usually seed freely ; the seed should be sown 

 in March in heat, bringing the young plants 

 forward in the same temperature till May, 

 when they may either be transferred to the 

 borders of the flower-garden to be trained 

 against a wall, or suffered to creep over rock- 

 work, or they may be placed in large pots 

 having a trellis attached, where they form 

 very ornamental subjects for the green-house 

 through the summer. The remaining species, 



THU 



as they do not produce seed in any quantity, 

 require to be grown in the green-house. 

 They should be frequently syringed to keep 

 down attacks of red spider. At the end of 

 the growing season they should be pruned 

 closely back and kept dormant through the 

 winter. The green-house species, T. chrysops, 

 however, does better when allowed to grow 

 on without pruning, nor should it be re-potted 

 more than once a year, or it will not flower. 

 The pure white, T.fragrans, is a free-growing 

 green-house species, and its flowers are last- 

 ing and very sweet. T. laurifolia {syn. T. Har- 

 risii), with flowers tubular in form and two 

 inches in length, of a bright porcelain blue, 

 with yellow throat, is one of the best green- 

 house climbers we have. It is a rapid grower 

 and blooms in profusion from November to 

 May, its rare blue color making it one of the 

 most attractive green-house, climbing plants. 

 The beautiful, climbing, green-house plant, 

 known in cultivation as Hexacentris Mysorensis, 

 is by some botanists placed under this genus. 

 Me.yenia erecta, introduced from western Africa 

 in 1857, has also been placed here, though both 

 are better known in cultivation by the names 

 given above, and under which we have de- 

 scribed them in this work. 



Thu'nia. Derivation of name not given. Nat. 

 Ord. OrchidaceoE. 



A small genus of Orchids from tropical Asia, 

 formerly referred to Phajus, from which genus 

 they are, however, readily distinguished by 

 their growth, and by several other differences of 

 a botanical character. T. a^&a is one of the best 

 known species; the stems of this plant are 

 round and usually about two feet high, clothed 

 with leaves from the base upwards. The 

 flowers are produced on a short, terminal 

 raceme just as growth is flnished; the sepal 

 and petals are pure white; lip white, beauti- 

 fully pencilled along the centre with purple 

 and lilac. The species require to be grown ia 

 considerable heat and treated liberally with 

 water. They do better when grown in pots 

 than on blocks. 



Thu'ya. Arbor Yitse. From thyon, a sacrifice ; 

 the rosin of the Eastern variety is used instead 

 of incense at sacrifices. Nat. Ord. Conifera. 



This well-known genus of evergreens in- 

 cludes some of the most beautiful and useful 

 evergreen shrubs we have in cultivation, not 

 only for single plants for the lawn, but for 

 hedges, either high or low, for which they are 

 most admirablyadapted. The common Arbor 

 Vitee, T. occidentalis, is the parent of most of 

 the varieties grown for ornamental purposes. 

 It is common from New York to Maine, in 

 moist or swampy lands. In some localities it 

 makes a tree of considerable size, valuable for 

 the timber it yields, known as White Cedar. 

 Of this species there is a beautiful sport, of 

 globular form, with golden, green foliage, 

 known as Parson's Arbor Vitee, It is of slow 

 growth, broad and compact, and suitable for 

 cemeteries or any situation where a beautiful 

 evergreen is wanted. Hovey's Arbor Vit» is 

 a seedling from the common Arbor Vitffi. Its 

 dwarf, compact habit of growth makes it a 

 splendid plant for growing in tubs for winter 

 decoration. There are other varieties, with 

 golden foliage, which are very beautiful. The 

 Siberian Arbor Vitffi is one of the best for 

 hedges or lawns. It is perfectly hardy, has a 

 deeper color, is more compact, and in most 



