476 ANGIOSPERMAEMONOCOTYLEDONES 



the flower closes. The anther of the long stamen is yellow, like those of the 

 shorter ones. ' 



2835. H. Kotschyana Fenzl (=H. callaefoHa Reichb.). Kirk states that this 

 species possess cleistogamous flowers. Solms-Laubach also found these in several 

 other species of Pontederiaceae, some indigenous to America and some to Africa. 



CXVI. ORDER COMMELINACEAE BENTH. ET HOOK. 



923. Commelina Plum. 



Literature. Herm. MuUer, Kosmos, Leipzig, i, 1883, pp. 241-59; Breiten- 

 bach, op. cit, iii, 1885, p. 40 et seq. Cf. on division of labour of the stamens in this 

 genus and Tinnantia, Vol. I, p. 108. 



2836. C. benghalensis L. Weinmann (Bot. Ztg., Leipzig, xxi, 1863) says 

 that this species possesses subterranean cleistogamous flowers. 



2837. C. tuberosa L. (MacLeod, Bot. Jaarb. Dodonaea, Ghent, ii, 1890, 

 pp. 118-47.) This species, and others of the genus (C. Karawinskii (?), C com- 

 munis (.?)), are fertile at Ghent. 



Visitors. MacLeod observed 3 bees (i. Apis; 2. Bombus agrorum F.; 3. 

 Halictus sp.), 2 hover-flies (Syritta sp., and Eristalis tenax Z.), and the butterfly 

 Pieris napi Z. 



2838. C. coelestis Willd. Kemer (* Nat. Hist. PI./ Eng. Ed. i, II, p. 357) 

 says that in the ephemeral flowers of this species autogamy finally takes place by the 

 rolling up of the filaments and styles. 



924. Tradescantia Rupp. 



Kemer ('Nat. Hist. PI.,' Eng. Ed. i, II, p. 171) states that when the flowers of 

 species belonging to this genus fade their petals become pulpy, i. e. their surface is 

 covered with a thin layer of liquid by the exuding of cell-sap from the tissue, 

 which flies seek and lick off; in doing so they dust the stigma with foreign 

 pollen. 



2839. T. crassula Link et Otto, and 2840. T. virginiana L. Kemer (op. 

 cit., p. 308) describes these species as protandrous. 



CXVII. ORDER JUNCACEAE BARTL. 



This order has been so thoroughly examined and described by F. Buchenau 

 in his memoirs ' Monographia Juncacearum ' (Bot. Jahrb., Leipzig, xii, 1890, 

 pp. 1-495), ^'^^ *U. d. Bestaubungsverh. b. d. Juncaceen' (Jahrb. wiss. Bot., Leipzig, 

 xxiv, 1892, pp. 363-424), that I follow him entirely in my statements, which form 

 an abstract from these works, supplemented by some additions from Hermann Miiller 

 and O. Kirchner. 



The Juncaceae bear anemophilous flowers. Self-pollination is usually prevented 

 and cross-pollination made possible by protogyny (in some South American genera, 



II 



