316 



DATISCACE.L 



i DlCLINOVK EXOGENS. 



Ordeu CVI. DATISCACEiE.— Datiscads. 



Datisceje, R. Brown in Denham, 25. (1826); Bartl. Ord. Nat. ibj. (1830) ; Bndl. Gen. clxxxiv.; 



Meitner, p. 346. 



Diagnosis.— Cucurbital Exogens with apetafous flowers, strictly parietal placenta. 



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, <J $ . Calyx of the <J divided into 3-4 pieces ; of the <j> adherent 



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

 branous, linear, bursting longitudinally. £ Ovary l- 

 celled, with Z-\ pulyspermous 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 polyspennous 

 parietal placentae. Seeds enveloped in a membranous 

 finely reticulated integument, with a cupulate membra- 

 naceous strophiole ; embryo straight, without albumen, 

 its radicle very long, turned towards the liilum. Cotyle- 

 dons very short. 



The many-seeded capsule of this genus, with parietal 

 placentae, and open at the apex, naturally suggested its 

 relationship to Reseda, with which, however, it really 

 has no other point in common. The foliage and manner 

 of growth of Datisca cannabma has in like manner led 

 to the equally wrong conclusion that it might have some 

 > ^r^\1'/ iWftJFf^iX connection with Hempworts. An anonymous writer 



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

 be between Cucurbits 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 flowers, 

 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, indeed, that Datisca and Tricerastes 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 flowering in loose terminal panicles, 

 and the oblique leaves of Tetrameles, are 

 equally characteristic of Begonia. 

 Fresenius asserts (Liauwi, 1839) that female plants of Datisca cannabma are capable 

 of bearing seed, although entirely 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 Order, 

 consisting otherwise of annual stemmed herbaceous plants. 



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

 America, Siberia, Northern India, the Indian Archipelago, and the south-eastern 

 corner of Europe. 



Fig. C'cxiv — Tricerastes glomerate. — Prcsl. 1. 3 of Datisca canuabina ; 2. its fruit; 3. across 

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





CCX1X. 



