374 ANGIOSPERMAE— DICOTYLEDON ES 



length. The anthers open completely in dry weather, but close again when it is 

 damp. 



2558. U. montana With. (Kirchner, ' Beitrage,' p. 1 2 ; Knuth, ' Bloemenbiol. 

 Bijdragen.') — The two red filiform stigmas in this species are mature when the 

 flowers open, and project beyond the anthers, which are still immature and provided 

 with short filaments. The latter elongate later on, so that the stigmas are hidden 

 among the stamens ; the anthers then dehisce, and the stigmas, which are still 

 receptive, may be fertilized by automatic self-pollination if they have not already been 

 dusted with foreign pollen in the first stage of anthesis. The flowers, united in 

 crowded clusters, do not as a rule mature simultaneously, so that blossoms in various 

 stages of maturation are found on the same cluster. Warnstorf describes the pollen- 

 grains as white in colour, irregularly rounded-polyhedral, with uneven undulating 

 ridges, about 30-7 yn in diameter. 



Visitors. — Sprengel (' Entd. Geh.,' p. 150) observed the honey-bee, and it is 

 recorded as freq., po-cltg., by Kirchner (Stuttgart), and Knuth (Kiel). 



2559. U. campestris L. (Kirchner, op. cit., p. 1 3 ; Kerner, ' Nat. Hist. PI.,' 

 Eng. Ed. I, II, p. 311.) — The flower mechanism of this species agrees with that of 

 the preceding one. Kerner says that the stigmas force their way out of the still 

 closed flowers. 



Visitors. — Knuth observed the honey-bee, freq., po-cltg. 



2560. U. pedtmculata Fouger. (= U. effusa Willd., and U. ciliata Ehrh.). 

 (Schulz, ' Beitrage.') — The anthers and stigmas in this species mature in the same 

 order as those of the two preceding ones. Schulz describes the perianth as bilaterally 

 symmetrical ; and in correspondence with this the anterior style is longer than the 

 other. The two stigmatic branches, partially projecting from the perianth, are beset 

 with a brush-like tuft of long white or reddish papillae, to which the pollen-grains 

 readily adhere. These are yellowish-white in colour, irregularly rounded-polyhedral, 

 beset with ridges, about 30-5 /x in diameter. 



797. Celtis Tourn. 



2561. C. australis L. (A. Francke, 'Beitrage.') — This South European 

 species is andromonoecious, with protogynous hermaphrodite flowers and earlier 

 maturing male ones. 



XCIX. ORDER PLATANACEAE LESTIB. 



798. Platanus L. 



Flowers anemophilous ; monoecious. Kerner states that the female flowers 

 mature before the male ones. He also says ('Nat. Hist. PI.,' Eng. Ed. 1, II, pp. 117, 

 133, 146) that the stamens are claw-shaped, each possessing a shield- or cushion- 

 shaped connective broadening out above the anthers. At the base of the globular, 

 pendulous inflorescence, many of these stamens are crowded together, and their 

 connectives make up a sort of roof. Under this roof are spaces in which the 

 dehisced pollen is stored for a time. As the stamens fall singly from the inflorescence, 



