250 ANGIOSPERMAE—DICOTYLEDONES 



XXX. ORDER AMPELIDEAE H. B. K. 

 Small, green, but fragrant flowers, homogamous or protandrous. 



187. Ampelopsis Michx. 

 Protandrous flowers with concealed nectar, secreted at the base of the ovary. 



622. A. quinquefolia Michx. — Kirchner ('Flora v. Stuttgart,' p. 362) states 

 that the nectar is secreted in minute drops under the base of the ovary. After the 

 flower has opened the green petals become completely reflexed, while the five 

 stamens become erect, and their anthers dehisce introrsely. These then turn their 

 pollen-covered surfaces upwards, and at this stage project about i mm. beyond the 

 still immature stigma. The stigma does not become receptive until the petals and 

 stamens have dropped off. 



Visitors. — Kirchner observed the honey-bee. I myself observed Lucilia caesar 

 L. at work on the anthers. According to Kerner (' Nat. Hist. PI.,' Eng. Ed. i, II, 

 p. 206), the flowers are much visited by bees, attracted by an odour which is 

 imperceptible to us. Plateau also noticed Apis in Belgium. 



188. Vitis L. 



Flowers homogamous, with exposed nectaries. Perhaps there is also wind- 

 pollination. Focke (Abh. natw. Ver., Bremen, xiv, 1897, p. 302) states that some 

 of the species are androdioecious. According to Beach (Bot. Gaz., Chicago (III), 

 xvii, 1892), self-pollination frequently takes place in the still unopened flowers. 



623. V. vinifera L. (Kirchner, 'Flora v. Stuttgart,' p. 361; Rathay, see 

 Bibliography ; Kronfeld, Ber. D. bot. Ges., Berlin, vii, 1889, p. 42 ; Knuth, ' Bloemen- 



biol. Bijdragen.') — The inconspicuous, small, yellowish- 

 green flowers of this species attract insects by their 

 delightful odour. At the base of the ovary, between 

 the filaments, are five (more rarely six) yellow, fleshy 

 nectaries. The flowers, as is well known, open by the 

 five (rarely six) green petals becoming detached at 

 the base, and fallmg off in the form of a cap. The 

 five (or six) stamens spread out, and the upper sides 

 of the anthers become covered with pollen. The 

 stigma matures simultaneously, but, according to 



Fig. 77. ViiisvirtiYera, L. (From tt ■ x, ■ . ' ° 



nature.) t;, nectary. Kirchner, rcmams receptive after the anthers have 



withered. As it is at a lower level than the anthers, 

 automatic self-pollination is possible, and Kirchner says that it is effective. 



Rathay asserts that the five nectaries are non-functional, but according to 

 Delpino, they secrete freely. Portele says that the stigmatic secretion is strongly 

 saccharine, but Rathay was only able to find traces of grape-sugar. The latter 

 authority considers the vine to be anemophilous— because he proved that the wind 

 can carry away individual pollen-grains from the dehisced anthers (' Geschlechtsver- 

 haltnisse der Reben,' I, pp. 31 et seq.)— and entomophilous as well— for he observed 



