i8o ANGIOSPERMAE—DICOTYLEDONES 



AIL), with calyx-teeth projecting beyond the small corolla (Maximovicz) ; (3) inter- 

 mediate, with a scarcely open corolla hardly projecting beyond the calyx-teeth 

 (Urban). Forms (i) and (2) may be associated on the same plant. In chasmo- 

 gamous flowers the filaments of the two long stamens are so bent that their 

 anthers lie above those of the two short ones, which are only about half as long : the 

 anthers have long appendages, and the style projects considerably beyond them. 

 The appendages of the anthers of cleistogamous flowers from the same plant 

 (growing at Regensburg) were, on the contrary, very short ; the anterior stamens 

 possessed straight filaments, and were a little longer than the posterior ones, of 

 which the filaments were slightly curved ; and the anthers were applied to the 

 stigma, situated at the end of a straight style about one-third as long. In Central 

 and South Europe both forms of flower possess free anthers ; in Asia these are 

 usually adherent, while at the same time they are arranged in pairs under the 

 upper lip owing to the curving of the filaments. This indicates a more marked 

 adaptation to cross-pollination. 



In temperate Europe and Asia cleistogamous flowers predominate, and are 

 rarely associated with chasmogamous ones on the same plant. In South and West 

 Europe chasmogamous flowers occur together with the more numerous cleistogamous 

 ones. The former only are to be found in Further India. 



658. Hysanthes Benth. 



2ogg. H. gratioloides Benth. (Urban, Ber. D. bot. Ges., Berlin, ii, 1884: 

 Loew, ' Bliitenbiol. Floristik,' pp. 290-1.) — This North American species, introduced 

 into France, bears both chasmogamous and cleistogamous flowers. The latter 

 possess a pale corolla considerably exceeded in length by the calyx-teeth, while the 

 two posterior stamens bend somewhat towards each other and the middle of the 

 flower. The anthers are thus brought to the two sides of the style and the stigma 

 with its ill-defined lobes, to which the pollen-grains adhere and into which their 

 pollen-tubes penetrate. The two anterior stamens are modified into staminodes, 

 represented in the chasmogamous flowers by short narrow threads, somewhat 

 thickened above, and corresponding to the appendages of the anthers. They 

 spring from glandular ridges in the lower part of the corolla-tube, and are them- 

 selves beset with glands. Each is continued into a much thinner thread, given 

 off at a variable height at a right or obtuse angle. Instead of the glandular 

 appendages the cleistogamous flowers possess only an inconspicuous swelling or 

 a small capitate process, behind which the true staminode appears in the form of 

 an oblique thread. 



659. Limosella L. 



2100. L. aquatica L. — Kerner states that when the small flesh-coloured 

 flowers of this species are submerged they remain closed, and fertilize themselves 

 pseudocleistogamously. 



660. Digitalis L. 



Protandrous humble-bee flowers ; with nectar secreted by an annular swelling 

 at the base of the ovary. 



