332 ANGIOSPERMAE—DJCOTYLEDONES 



2424. A. retroflexus L. — Warnstorf (op. cit.) says that the small, greenish, 

 diclinous (monoecious) flowers of this species are anemophilous. Male flowers occur 

 among the more numerous female ones. The latter possess three stigmas beset with 

 very large papillae. The anthers are greenish, and borne on delicate flaccid fila- 

 ments. The pollen-grains are whitish in colour, irregularly spheroidal, with numerous 

 germinating papillae, 31-3 ja in diameter. 



Visitors. — Plateau noticed a fly (Musca domestica L.) and a beetle (Cassida 

 nobilis Z.). 



LXXXVII. ORDER CHENOPODIACEAE VENT. 



Literature. — Sprengel, ' Entd. Geh.,' p. 7 ; Knuth, ' Bl. u. Insekt. a. d. nordfr. 

 Ins.,' p. 126; Volkens in Engler and Prantl, 'D. nat. Pflanzenfam.,' Ill, i a, p. 47 ; 

 Kirchner, Jahreshefte Ver. Natk., Stuttgart, xlix, 1893, P- i09- 



Flowers belonging to species of this order are hermaphrodite, or dioecious by 

 reduction. They possess a small, insignificant, calyx-like perianth, or are sometimes 

 quite naked. Insect-visits are therefore very rare, and the flowers are generally 

 anemophilous or self-pollinated. 



Sprengel describes Chenopodium and Beta as anemophilous. Volkens con- 

 siders that they are entomophilous : ' First of all, I think that wind-pollination can at 

 any rate only be of secondary importance. There are three reasons for this : first, 

 the pollen is not easily dispersable ; secondly, the order does not possess the slender, 

 limp, supple filaments, flower-stalks, or inflorescence-axes which are peculiar to 

 anemophilous flowers ; and thirdly, the course of anthesis does not agree with that 

 of other anemophilous flowers, in which not only all the flowers open more or less 

 simultaneously, but the anthers dehisce almost all at once. Nothing hke this occurred 

 in the plants of the order which I examined. If a plant belonging to Chenopodium 

 or Atriplex be observed towards autumn, it will be at once seen that of the hundreds 

 and perhaps thousands of flowers covering the stock, only a very few are completely 

 open. Anthesis goes on in this way for weeks, but the further maturation of the 

 ovaries usually takes place extraordinarily quickly ; thus towards the end of the 

 vegetative period there is scarcely any time at which all stages of the flower, from 

 bud to fruit, may not be found simultaneously on the same plant. 



' Also the flower itself does not open suddenly. Following the course of the 

 spiral, one perianth leaf after another spreads out, together with the stamen opposed 

 to it, the anther of which dehisces at the same moment and sheds its pollen. If the 

 facts quoted are against the theory of wind-fertilization, that of insect pollination is 

 favoured by the great attraction which at least our native species undoubtedly exert 

 upon various kinds of insects. Scarcely a plant of any species growing in the open 

 air is to be found in Germany, the flowers of which are not infested by an excessive 

 number of small bugs, aphides, flies, and other little animals which creep or crawl. 

 Whether these are merely attracted by the excellent hiding-places which the crowded 

 fasciculate inflorescences aff'ord, or whether the glandular disk, particularly in species 

 of Beta and Chenopodium, or the papillae covering this organ in many Salsoleae 

 provide food for them, I must leave undecided.' 



