488 ANGIOSPERMAE—MONOCOTYLEDONES 



and composed usually of four, more rarely of two or three roundish, opaque 

 grains. 



2904. T. angustifolia L. (Knuth, loc. cit.) — The flower mechanism of this 

 species is the same as that of the preceding one. Unisexual plants have not yet 

 been observed. 



2905. T. minima Hoflfm. (= T. Laximanni Lepech.). (Kerner, 'Nat. Hist. 

 PI.,' Eng. Ed. I, II, p. 313.) — Kerner says that the interval between the maturation 

 of the female and male flowers in this species is about nine days. 



938. Sparganium L. 



Protogynous, monoecious wind flowers, arranged in globular spikes. Warnstorf 

 describes the pollen-grains as of the same size and shape in all the species, yellowish 

 in colour, rounded, tetrahedral, with a network of tubercles, on an average 20 /a in 

 diameter. 



2906. S. ramosum Curt. (=S. erectum L.). (Kirchner, 'Flora v. Stuttgart,' 

 p. 83 ; Knuth, loc. cit.) — The globular female spikes in this species are situated 

 below the male ones and mature before them ; the stigma begins to shrivel when the 

 anthers of the small male spikes dehisce. The anthers are one mm. long and are 

 adnate to movable filaments about 3 mm. long. Each male spike possesses some 

 hundred stamens, and each female one 100-150 stigmas. Pollination is easily 

 effected by the wind, because the stigmatic branches are 3 mm. long, situated on 

 a style 2 mm. high, and therefore project widely. The diameter of the female 

 spike is thus increased to i\ cm. ; that of the male one is only about half as much. 



2907. S. simplex Huds. (W. J. Behrens, Flora, Marburg, New Sen, xxxvii, 

 1879; Knuth, loc. cit.) — The flower mechanism in this species is the same as that 

 of the preceding one, but the male and female spikes are smaller, and composed of 



fewer flowers. 



CXX. ORDER AROIDEAE JUSS. 



Literature. — Engler and Prantl, ' Araceae,' in ' D. nat. Pflanzenfam.,' 11, 3, 

 pp. 108-9; Knuth, ' Grundriss d. Bliitenbiol.,' p. 94. 



The hermaphrodite or unisexual flowers are closely crowded on a fleshy 

 axis, and form a spadix generally surrounded by a spathe. Insects are attracted 

 partly by this, partly by the inflorescence, and partly by a coloured, club-shaped 

 elongation of the spadix, or by several of these simultaneously. 



939. Arum L. 



Monoecious, protogynous, pitfall flowers. 



2908. A. maculatum L. (Delpino, 'Ult. oss.,' pp. 17-21 ; Hildebrand, Bot. 

 Ztg., Leipzig, xxviii, 1870, pp. 589, 591 ; Herm. Miiller, ' Fertlsn.,'p. 562 ; MacLeod, 

 Bot. Jaarb. Dodonaea, Ghent, v, 1893, pp. 292-3; Kirchner, 'Flora v. Stuttgart,' 

 p. 86 ; Christy and Corder, 'Arum maculatum ' ; Knuth, ' Bloemenbiol. Bijdragen.') — 

 In this species the upper part of the spathe, together with the thick, dark-red end of 



