462 ANGIOSPERMAE—DICOTYLEDONES 



of both kinds are associated in the same umbel, either in the same or in different 

 umbelluies. To this group belong, for example, Eryngium campestre L. and 

 T.aserpitium latifolium L. 



The two kinds of flower are only found on separate stocks in the case of 

 Trinia glauca Reichb. Even in this species, however, plants bearing both kinds 

 sometimes occur — the hermaphrodite flowers being generally in the minority — 

 either in all the umbelluies of all or some umbels, or only in some umbelluies, 

 as a rule of all the umbels. This variation is either associated with male and 

 hermaphrodite plants, or with male ones only, or it may be quite sporadic. In 

 the case of Trinia, hermaphrodite flowers may also be replaced by female. Female 

 flowers are much rarer than male ones in this order, and it appears that they are 

 not constantly present in any one species. They have been observed in the following 

 cases besides that of Trinia glauca — Eryngium campestre Z., Pimpinella magna Z., 

 P. Saxifraga L., and Daucus Carota Z. In Eryngium campestre and the two species 

 of Pimpinella, the female flowers either occur alone or together with neuter ones, but 

 are never associated on the same stock with hermaphrodite or male flowers. The 

 same is the case as a rule for Daucus Carota ; but in this species female flowers now 

 and then occur at the periphery of umbelluies bearing marginal hermaphrodite flowers 

 and central male ones. Not infrequendy the male flowers of the four species 

 mentioned are replaced by neuter ones, though throughout the summer they onlv 

 possess umbels bearing hermaphrodite flowers, or hermaphrodite and male ones, 

 or ultimately only male ones. Neuter flowers are of sporadic occurrence and in 

 some localities they appear to be wanting altogether. This also applies to the 

 case of Orlaya grandiflora Hoffm- The hermaphrodite flowers are protandrous in 

 most species, and in some protandry is so well marked that the styles and stigmas do 

 not attain their full development till after the stamens and petals have fallen off". 

 A number of Umbelliferae, however, bear flowers which are homogamous or but 

 shghtly protandrous. These are almost exclusively species that owing to the small 

 number and size of the flowers, and their indistinct white or greenish-white colour, 

 attract but few insect visitors, e.g. Aethusa Cynapium L., Caucaloides daucoides Z., 

 Torilis infesta Roth, Scandix Pecten- Veneris Z., and Anthriscus vulgaris Bernh. 

 In the favourite habitats of these species, among corn or dense brushwood, there are 

 but few insects that visit flowers. It is more remarkable that Anethum graveolens Z. 

 is a homogamous species, for though its flowers are small and produce but little 

 nectar, their brilliant yellow colour makes them very conspicuous, and they possess 

 a powerful aromatic odour. To the foregoing autogamous species I would add 

 Helosciadium inundatum Koch (cf Knuth, ' Bl. u. Insekt. a. d. nordfr. Ins.,' p. 78) and 

 Hydrocotyle vulgaris L. 



Drude distinguishes the following ways of distribution of the sexes, and order of 

 maturation of stamens and carpels (in Engler and Prantl, ' D. nat. Pflanzenfam.,' Ill, 

 8, pp. 89-91).— 



A. Flowers monomorphous, all hermaphrodite (except in the feebly developed 

 umbels of higher order). 



I. Flowers almost homogamous, the two sexes developing in rapid succession ; 

 e.g. Hydrocotyle vulgaris Z., Anethum, Aethusa, and others. 



