LEGUMINOSAE 341 



235. Apios Moench. 



811. A. tuberosa Moench. — According to Loew's investigations (Flora. Mar- 

 burg, Ixxiv, 1 891) this species bears Lepidopterid flowers in which the carina, 

 pp. 160-71, is fixed, and there is no mechanical union between it and the alae. The 

 protrusion of anthers and stigma from the carina, which is the usual way of dusting 

 the ventral surface of visitors and effecting pollination, is thus rendered impossible. 

 In place of this mechanism the flower has acquired another method of securing cross- 

 pollination, by the remoteness of stigma and anthers from one another, and besides, 

 the nectar passages are shorter and more accessible, so that insects can suck more 

 easily. (Cf. p. 261.) 



236. Alhagi Tourn. 



812. A. camelonun Fisch. — 



Visitors. — Morawitz saw the Buprestid Sphenoptera karelini Falderm. in the 

 Caucasus. 



2. SUB-OKDEK Caesalpiniaceae R. Br. 



Flowers bilaterally symmetrical (zygomorphous). Scarcely or not at all papi- 

 lionaceous. Petals 5, sometimes entirely or partly absent; stamens 10, frequently 

 fewer or more (2-15), free or united in various ways; some of them may be sterile. 



237. Gleditschia !.. 



Inconspicuous green flowers which secrete nectar abundantly in the hollow 

 of the calyx. The hermaphrodite flowers are protogynous. 



813. G. triacanthos L. — Kirchner (' Neue Beob. ii. d. Bestaubungseinricht. 

 einheimisch. Pfl.,' Stuttgart, 1886) says that the fragrant richly nectariferous flowers 

 of this species are monoecious-polygamous, and possibly dioecious. The four green 

 sepals and petals are united below into a cup, which secretes nectar abundantly 

 on its inner surface. It is protected by hairs on the bases of the stamens. The 

 hermaphrodite flowers are protogynous. The hairy elongated ovary bears a large 

 terminal stigmatic cushion, which projects several millimetres from the flower, while 

 the stamens are still enclosed in the perianth. The male flowers usually possess 

 5-7 projecting stamens, and there is no trace of a pistil. The female flowers bear 

 stamens with vestigial anthers. 



Visitors. — Kirchner noticed numerous insects, especially bees. 



238. Cercis L. 



814. C. Siliquastrum L. — 



Visitors. — Loew noticed honey-bees, skg., in the Beriin Botanic Garden. 



239, Parkinsonia. 



815. P. aculeata L. — Lanza ('Note di biologia fiorale,' 1894) states that this 

 species is dichogaraous in the Palermo Botanic Garden. The vexillum of the 

 fertilized flower changes colour. 



Visitors. — Lanza observed Xylocopa cyanescens Brull. 



