ARISTOLOCHIA CEAE 



355 



2496. A. Ruiziana Duch. (= A. Duchartrei Andre); and 2497. A. elegans 



Mast. These two species are tropical. Correns says (op. cit.) that there are two 

 areas in the pit which are more thickly covered with hairs than the rest, and may be 

 considered as nectaries. As the weel-hairs are only one-third as long as the lumen 

 of the perianth tube, the barrier apparatus is formed by two projections. The hair 

 thus touches the perianth wall at two separate points, one to the right and the other 

 to the left of the joint, and is therefore able to resist lateral impact. 



2498. A. grandiflora Sw. (Delpino, op. cit.) This species is indigenous to 

 the Antilles, and is distinguished by its wine-red colour and smell of carrion, which 

 facts give rise to the supposition that the very large flowers are visited by carrion-flies. 

 A tendril proceeding from the perianth limb winds round an adjacent branch to hold 

 the flower in the right position for insect visitors. 



772. Asarum L. 



The blossoms of species belonging to this genus are protogynous and not very 

 conspicuous ; Hermann Miiller describes them as nauseous flowers (Kosmos, Leipzig, 

 iii, 1878). He considers that they perhaps act as prisons or at least as hiding-places 

 for insect visitors, and so form a stage leading up to the mechanism of Aristolochia 

 {cf. Vol. i, p. 128). 



2499. A. europaeum L. (Delpino, 'Altri appar. dicog. recent, oss.,' pp. 61-2; 

 Herm. MuUer, 'Fertilisation,' p. 517, Kosmos, Leipzig, iii, 1878; Kerner, 'Nat. 

 Hist. PI.,' Eng. Ed. i, 

 II, p. 279; Kirchner, 

 'Flora V. Stuttgart,' p. 

 520 ; Knuth, ' Bloemen- 

 biol. Bijdragen.') The 

 flowers of this species 

 grow singly close to the 

 ground often hidden by 

 fallen leaves. They are 

 of a greenish - brown 

 colour outside and dirty- 

 red brown inside, not 

 very conspicuous, and 

 possessing a sharp, cam- 

 phor-like odour. The 

 three perianth lobes open 

 slowly, in such a way 

 that their tips remain 



for some time curved inwards, while they spread out below. Three small cleft- 

 like entrances to the interior of the flower are thus formed, behind which the 

 already mature stigmas are situated, so that they must be touched by insects on 

 entering. Kerner says the visitors are small flies. The hexamerously arranged 

 stigmatic lobes bear (according to Kirchner) tufts of stigmatic papillae facing out- 

 wards. In the first stage of anthesis the twelve stamens, arranged in two whorls, are 



A a a 



Fig. 357. Asarum europaeum, L. (after Herm. Muller). . Young 

 flower, just opening ; half the perianth removed. //. Older flower ; the 

 most anterior short stamens are beginning to erect themselves and dehisce. 

 a' and a^, longer and shorter stamens ; _/f, filaments ; st, stigmas. 



