TKTfi] 



€i)t (Ereagurg at 28atamn 



1136 



mnus; the calyx-tube is hemispherical, 

 connate with the ovary, its limb truncate 

 or slightly five-toothed ; petals seven to 

 eight, epigynous, slightly coherent, ca- 

 ducous ; stamens inserted with the petals, 

 and four times as numerous (twenty-eight 

 to thirty-two), the filaments short ; ovary 

 seven to ten-celled, style none; stigma 

 obscurely radiated; fruit baccate, with 

 eight to ten one-seeded stones. The ge- 

 neric name is derived from the Greek 

 tetraplasios 'fourfold' and andra 'a sta- 

 men.' [M. T.M.] 



TETRAPLEURA. A genus of legumi- 

 nous plants, consisting of one species, T. 

 Tlwnningii, a large tropical "West African 

 tree, with opposite v bipinnate leaves, 

 and spikes of flowers agreeing in their 

 technical characters with those of Ade- 

 nanthcra, to which genus, in fact, the plant 

 was formerly referred under the name of 

 Adenanthera tetrapiera. It is, however, 

 distinguished by the singular form of its 

 pods, which are hard and woody, of a deep 

 mahogany-colour, and beautifully polished. 

 They are blunt at the ends, flattened, 

 slightly curved, with thin sharpish edges ; 

 and have an elevated ridge of the same 

 form and structure as the edges of the 

 pod, running along the middle of both flat 

 sides throughout their entire length, so 

 that at first sight they appear like four- 

 winged pods. Inside they are transversely 

 divided into a number of distant one- 

 seeded cells, the seeds being egg-shaped, 

 flattened, about the size of tamarind- 

 seeds, and surrounded by a pulpy sub- 

 stance, which the natives of the Zambezi 

 River in Eastern Africa employ as a deter- 

 gent. [A. SJ 



TETRAPOMA. A genus of Cruciferce 

 founded on the Camelina barbaria/olia. 

 The genus, however, is more nearly allied 

 to Cochlearia, from which it differs chiefly 

 by the pouch being four-valved, one-celled, 

 with four rows of seeds. They are an- 

 nuals or biennials, inhabiting Siberia and 

 North-western America, having the habit 

 of Nasturtium amphibium. [J. T. SJ 



TETRAPTEROTJS. Four-winged. 



TETRAPTERYGIUM. A genus of Cru- 

 ciferce, consisting of a smooth glaucous 

 herb, growing in Armenia. It differs from 

 Isatis in the cordate pouch, which has also 

 two narrow wings on the disk, so that it is 

 four-winged. [J- T. S.] 



TETRAPYRENOTJS. Pour-stoned. 



TETRAQUETER. Having four very 

 sharp and almost winged corners. 



TETRASPORE. In the rose-spored 

 Algce two forms of fructification are uni- 

 formly found— the one capsular, in which 

 spores are fertilised by impregnation ; 

 the other consisting of little clusters of 

 spores, in most cases four in number, but 

 very rarely eight. This form of fruit 

 does not seem to be a mere modification 

 of the capsule, but rather to be of the 

 nature of gemmae, multiplying the in- 



dividual without impregnation. It is 

 called tetrasporic, and the separate bodies 

 tetraspores. They are usually formed by 

 the division (often unequal) of one globose 

 endochrome, three of the four divisions 

 only being in general visible, in which 

 case the fruit is sometimes erroneously 

 called trisporic. When all four are visible 

 at once the division is said to be crucial. 

 In some genera, however, the oblong or 

 elliptic endochrome is divided transverse- 

 ly, when the division is called zonate or 

 annular. The tetraspores may be simply 

 immersed in the frond, when they are 

 called sori ; or contained in external warts 

 cr excresences (hemathecia), or in proper 

 leaflets (sporophylla), or, lastly, in elon- 

 gated pod-like processes (stichidia). In 

 the genus Seirospora they are disposed in 

 necklace-like branched strings. Decaisne 

 was inclined to consider the tetrasporic 

 fruit as the normal fruit, and the concep- 

 tacular as gemmate ; but in this he has not 

 been followed by algologists. [M. J. B.J 



TETRASPORIC. Composed of tetra- 

 spores. 



TETRASTICHOUS. Having a four-cor- 

 nered spike. 



TETRATHECA. A genus of Treman- 

 dracece, inhabiting Tasmania and the 

 southern parts of the Australian Conti- 

 nent, and composed of twenty species of 

 heath-like shrubs, having small linear lan- 

 ceolate or ovate leaves, generally arranged 

 in whorls ; axillary solitary flowers, of 

 a purple yellow or white colour, and pos- 

 sessing- the peculiarity of only opening in 

 a bright sun or on fine days, but closing 

 when it is going to rain and on the ap- 

 proach of evening ; whilst those of the 

 allied genus Platytheca are not affected 

 by any meteorological or astronomical 

 changes. The calyx is four to five-cleft ; 

 the corolla composed of four or five petals ; 

 the stamens are from eight to ten in num- 

 ber, the anthers two or four-celled ; and 

 the capsule obovate and two-celled. Se- 

 veral species have been introduced in our 

 greenhouses. [B. SJ 



TETRATOME. A genus of Monimiacece, 

 consisting of trees or shrubs, with uni- 

 sexual dioecious flowers. The males have 

 a somewhat bell-shaped perianth, dilated 

 at the throat, while the limb is divided 

 into four segments, two of which are pro- 

 vided with a jagged appendage ; and the 

 stamens are numerous, inserted on the 

 perianth in four rows. The females have 

 a bell-shaped perianth, equally four-cleft 

 above, adherent below to the ovaries, 

 which are numerous, attached to the 

 interior of the perianth, each having 

 one cell containing a single pendulous 

 ovule. The fruits are drupe-like, and very 

 small. The generic name is derived from 

 the Greek tetra 'fourfold' and tome 'a 

 segment,' in allusion to the four-parted 

 perianth. The species are natives of Tro- 

 pical America. [M. T. MJ 



TETTER-BERRY. Bryonia dioica. 



