316 



DATISCACE^. 



[Diclinous Exogens 



Order CVI. DATISCACEiE.— Datiscads. 



Datisceas, R. Brown in Denham, 



Diagnosis.- 



25. (1826); Bartl. 

 Meisner, p. 



Ord. Nat. 

 346. 



419. (1830) ; Endl. Gen. cLxxxiv. ; 



-Cmurhital Exogens with ajietalous floioers, strictly parietal placenta, and 

 dry fruit. 



Herbaceous branched plants; or trees of considerable size. Leaves alternate, 

 cut, simple, or compound, without stipules. Flowers in axillary racemes or ter- 

 minal panicles, ^ $ . Calyx of the <J divided into 3-4 pieces ; of the $ adherent 

 3- 4-toothed. $ Stamens 3-7 ; anthers 2-celled, mem- 

 branous, linear, bursting longitudinally. $ Ovary 1- 

 celled, with 3-4 polyspermous parietal placentae ; ovules 

 anatropal ; stigmas equal in number to the placentae, 

 and opposite the lobes of the calyx. Fruit capsular, 

 opening at the vertex, 1 -celled, with polyspermous 

 parietal placentae. Seeds enveloped in a membranous 

 finely reticulated integument, with a cupulate membra- 

 naceous strophiole ; embryo straight, without albumen, 

 its I'adicle very long, turned towards the hilum. Cotyle- 

 dons very short. 



Tlie many-seeded capsule of this genus, \f\i\\ parietal 

 placentae, and open at the apex, naturally suggested its 

 relationship to Reseda, with which, however, it really 

 has no other point m common. The foliage and manner 

 of growth of Datisca cannabina has m like manner led 

 to the equally WTong conclusion that it might have some 

 connection with Hempworts. An anonymous writer 

 in the Linncea (xiv. 262) has suggested its station to 

 be between Cucui'bits and Loasads. This seems 

 to have been a close approach to the truth. It is, 

 however, with Begonia that it corresponds most nearly, 

 and it will have to follow the fate of that Order, whether 

 allowed to retain the station now assigned to it or 

 removed to some other place. The unisexual flowei's, 

 numerous minute seeds, orthotropal embryo without 

 albumen, and adherent calyx of these two Orders, afford 

 very strong marks of relationship ; to which may be 

 added the triple placentation of two out of 

 three of the known Datisceous genera. It is 

 true, uideed, that Datisca and Ti'icerastes are 

 said to have albumen ; but I can find none 

 in Datisca nepalensis when fully ripe, and 

 therefore it may be doubted whether it exists 

 at that time in Tricerastes, or Datisca canna- 

 bina. To this it may be added that the naked 

 mode of flowermg in loose terminal panicles, 

 and the oblique leaves of Teti"ameles, are 

 equally characteristic of Begonia. 

 Fresenius asserts (Linnce/j, 1839) that female plants of Datisca cannabina are capable 

 of bearing seed, although entbely cut off from the males. He regards this property to 

 depend upon a mere act of vegetable increment, which, upon the supposition that 

 an embryo is a bud, is not inconceivable. Tetrameles, the Weenong of Java, and 

 Jungle Bendy of Bombay, is remarkable as being a large tree in this very small Ordei', 

 consisting otherwise of annual stemmed herbaceous plants. 



The very few species of which the Order consists are scattered over North 

 America, Siberia, Northei'u India, the Indian Arcliipelago, and the south-eastern 

 corner of Europe. 



Fig. CCXIX.— Tricerastes glomerata.—P>Yj?. 1. c? of Datisca cannabina; 2. its fruit; 3. across 

 section of it; 4. a seed; 5. its embryo. 



