256 



ANGIOSPERMAE—DICOTYLEDONES 



igo. Melianthus L. 



630. M. major L. — Francke describes the flowers of this species as protandrous 

 (' Beitrage z. Kennt. d. Bestaubungseinricht. d. Pfl.'). 



2. Sub-order Acerineae. 

 This suborder is represented in Europe only by the genus. 



191. Acer L. 



Several or many of the small greenish-yellow flowers are crowded together into 

 inflorescences, and thus rendered conspicuous. Some species blossom before the 

 leaves unfold, by which the same end is attained to a marked degree. Nectar is 

 secreted by a thick fleshy central disk, and is fully exposed. The flowers therefore 

 belong to class E. They are usually monoecious, rarely dioecious. 



631. A. platanoides L. (Herm. Miiller, ' Weit. Beob.,' II, pp. 212-13; Kirchner, 

 'Flora V. Stuttgart,' p. 351; Wittrock, Bot. Centralbl., Cassel, xxv, i886, p. 55; 

 K. Fr. Jordan, Ber. D. bot. Ges., Berlin, v, 1887 ; Knuth, 'Grundriss d. Bliitenbiol.' ; 



Fig. 79. Acer, L. (After F. Pax.) Flowers of various species in lonjritudinal section. A ^^ B ^, 

 ofA. Negundo. C and Z?, do. of A. Pseudo-PIatanus. .£". A. Hookeri. i^ A. campestre. 



Wamstorf, Schr. natw. Ver., Wernigerode, xi, 1896.) — The flowers appear beiore the 

 leaves in this species. The stamens, usually eight in number, arise from pits in 

 the fleshy disk, which is covered with minute drops of nectar lying quite exposed. 

 Wittrock states that the inflorescences are of five kinds, according to the distribution 

 of the male and female flowers on the inflorescence. These are composed, respec- 

 tively, of:— I. female flowers exclusively; 2. the flowers first developed are female, 

 and the later ones male ; 3. the earliest flowers are male (at the apex), then follow 

 male and female, and the last to open are mostly male; 4. male flowers are 

 first developed, and then female; 5. all the flowers are male. Only one of these 

 varieties of inflorescence is found on most trees, but two, or even three of them, may 

 be associated on the same tree in exceptional cases. The commonest kind is 2 

 (about 40 % in the trees examined by Wittrock), then follow in order 4 (22 %), 

 5 (12%), 3 (4%), I (not quite 1%). 



The female flowers possess stamens that appear normal, as do the numerous 

 pollen-grains contained in the anthers, which, however, never dehisce. The filaments 



