m\ 



364 ANGIOSPERMAEDICOTYLEDONES 



immediately above the stigma, so that automatic self-pollination by fall of pollen 

 inevitable. The size of the pollen-grains and stigmatic papillae does not va 

 essentially in the two forms. Homostylous flowers also occur sometimes. 



Although the honey-odour is not particularly strong to our sense of smell, it is 

 so extremely attractive to bees, that (according to Schulz) these insects neglect all 

 other flowers, however brilliant in colour, if nectar is not so abundant in them as in 

 this species. This investigator saw bees fly straight to this plant from a distance 

 of from 40 to 50 m., or even further ; they could not have seen anything of its leaves 

 or flowers, but they passed over numerous others, blue and red in colour, which they 

 did not despise at other times. Schulz concluded, therefore, that it is not the colour, 

 as is generally supposed, but the specific smell of nectar which forms the chief 

 attraction to visitors. 



Visitors. Schulz (Halle and S. Tyrol), many small bees, flies, and beetles, and 

 a few Lepidoptera. ^j 



2518. T. pratense Ehrh. (Kirchner, 'Flora v. Stuttgart,' p. 521; Hermp' 

 Miiller, ' Weit. Beob.,' II, p. 235.) The perianth in this species is green outside 

 and white inside, and 5-6 mm. in diameter. The flowers are homogamous, but the 

 stigma is persistent. It outlives the stamens and is stUl receptive when the anthers 

 have shrivelled and fallen. These dehisce introrsely and become covered all over 

 with pollen. The stamens are of the same length as the stigma, and situated very 

 near it, so that self- and cross-pollination may be effected with equal facility by insects 

 probing for the nectar secreted at the base of the flower. Should such visits fail, 

 automatic self-pollination may easily take place in consequence of the proximity and 

 simultaneous maturation of stigmas and anthers. 



Visitors. Herm. Miiller observed the honey-bee, skg. 



2519. T. bavarum Schrank (= T. montanum Ehrh.). Kirchner, ' Flora v. 

 Stuttgart,' p. 522.) The flower mechanism of this species resembles that of the 

 preceding one, but the stigma projects about a mm. beyond the anthers, so that 

 cross-pollination is favoured by insect-visits, and automatic self-pollination rendered 

 difficult should these fail. 



XCVII. ORDER EUPHORBIACEAE JUSS. 

 782. Buxus L. 



Flowers monoecious with exposed nectar, probably occasionally anemophiloi 

 2520. B. sempervirens L. (Herm. Miiller, 'Weit. Beob.,' II, pp. 214-15' 

 Kemer, 'Nat. Hist. PI.,' Eng. Ed. i, II, pp. 138, 173, 313; Warnstorf, Verb. bot. 

 Ver., Berlin, xxxviii, 1896; Knuth, ' Bloemenbiol. Bijdragen.') The flowers of this 

 species are yellowish-green in colour, and therefore rather inconspicuous. They are 

 also odourless, but the yellow anthers of the male flowers, which protrude while the 

 bud is still closed, are so conspicuous that visitors are fairly numerous, the plant 

 flowering so early in the year (March and April) that there are very few other floweift|| 

 at their disposal from which they can obtain nectar. f | 



The apical flower of the crowded spike is female ; it is surrounded by six or 

 more male ones, each of which possesses four thick anthers. Both kinds of flowei 



I 



