370 ANGIOSPERMAEDICOTYLEDONES 



786. Phyllanthus L. 



2543. P. Niniri L. (?) (Ludwig, Kosmos, Leipzig, i, 1872.) This species is] 

 indigenous to Brazil. At the base of the inflorescence are situated smaller whitishr 

 green, bell-shaped male flowers provided with nectaries, and above them the largei 

 green female ones with longer stalks, devoid of nectar. Anthesis begins by th 

 almost simultaneous opening of the male and female flowers situated in the lowea 

 part of the inflorescence. 



Visitors. Ludwig and Herm. Miiller supposed these to be small Diptera. 



787. Mercurialis L. 



Flowers anemophilous ; dioecious, rarely monoecious, still more rarely tri^ 

 monoecious. 



2544. M. annua L. (F. Heyer, Inaug.-Diss., Halle, 1883.) Heyer says tha^ 

 the ratio of male to female plants in this species is as 105-86 : 100 (on the average 

 calculated from 21,000 specimens). Monoecism occurs sometimes, single male 

 flowers appearing on the female plants, or conversely. Pollen is transferred bot 

 one plant to another by the wind. 



The development of germinable seeds without fertilization, i. e. parthenc 

 genetically, has already been described in Vol. I, p. 61.^ 



Visitors. The following were recorded by the observers, and for the localitie 

 stated 



MacLeod (Flanders), 2 hover-flies (Bot. Jaarb. Dodonaea, Ghent, vi, 189^ 

 p. 252). Plateau (Flanders), a Dermestid beetle (Anthrenus verbasci Z., freq^ 

 po-dvg.), Thrips, a moth (Botys sp.), and 4 hover-flies i. Syritta pipiens L.\ 

 2. Syrphus corollae Z. ; 3. Eristalis tenax Z. ; 4. E. arbustorum Z. 



2545. M. perennis L, (Thomas, Bot. Centralbl., Cassel, xv, 1883, p. 29 

 J. Saunders, J. Bot., London, xxi, 1883, pp. 18 1-2 ; Wamstorf, Schr. natw. Ver.) 

 Wernigerode, xi, 1896.) Thomas describes this species as dioecious, and occasion- 

 ally monoecious, while Saunders states that it is also sometimes trioecious. Wam-^ . 

 storf describes the male flowers as arranged in clusters of 4 to 7, grouped iivi 

 pseudo-spikes of which the apical flower opens first. The two globular, yellow 

 anthers, situated upon pale delicate filaments, diverge and dehisce upwards. The_^. 

 anther-lobes become indigo-blue in colour after the pollen-grains are scattered, I 

 These are sulphur-yellow in colour, closely tuberculate, ellipsoidal, on an average 



37 /x long and 20 /x broad. Kemer says that the stigmas of the female flowers are 

 receptive at least two days before the anthers of the male ones dehisce (' Nat. Hist. 

 PI.,' Eng. Ed. I, n, p. 403). 



* Juel (Vet.-Ak. Handl., Stockholm, xxxiii, 1900) says that in this species there is no rei 

 parthenogenesis (i. e. the development of a new individual from a cell which is morphologically an 

 unfertilized egg-cell), but only seed-formation without previous fertilization. This also applies to 

 Caelebogyne ilicifolia, /. Sm. (vol. i, p. 60), some species of Alchemilla (Murbeck, Bot Not., 

 Lund, 1897, p. 273), as well as to the plants of Antennaria alpina in the Innsbruck Botanic 

 Garden, which are described by Kemer as parthenogenetic. Juel (op. cit) proves by his investiga- 

 tions on the embryology of this plant that ' Kemer's hitherto unproved assertion of parthenogenesis 

 in Antennaria alpina is nevertheless true.' 



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