334 CLEISTOGAMIC FLOWERS. CHAi.VIIL 



species of Leersia only two stamens are fully de- 

 veloped ? * The anthers shed their pollen on the 

 stigma ; at least in one instance this was clearly the 

 case, and by tearing open the anthers under water 

 the grains were easily detached. Towards the apex of 

 the anther the grains are arranged in a single row and 

 lower down in two or three rows, so that they could be 

 counted ; and there were about 35 in each cell, or 70 

 in the whole anther ; and this is an astonishingly small 

 number for an anernophilous plant. The grains have 

 very delicate coats, are spherical and about y^^ of 

 an inch ('0181 mm.), whilst those of the perfect flowers 

 are .about 7 ^ s of an inch ('0254 mm.) in diameter. 



M. Duval-Jouve states that the panicles very rarely 

 protrude from their sheaths, but that when this does 

 happen the flowers expand and exhibit well-developed 

 ovaries and stigmas, together with full-sized anthers 

 containing apparently sound pollen ; nevertheless such 

 flowers are invariably quite sterile. Schreiber had pre- 

 viously observed that if a panicle is only half protruded, 

 this half is sterile, whilst the still included half is 

 fertile. Some plants which grew in a large tub of 

 water in my green-house behaved on one occasion in a 

 very different manner. They protruded two very 

 large much-branched panicles ; but the florets never 

 opened, though these included fully developed stig- 

 mas, and stamens supported on long filaments with 

 large anthers that dehisced properly. If these florets 

 had opened for a short time unperceived by me and 

 had then closed again, the empty anthers would 

 have been left dangling outside. Nevertheless they 

 yielded on August 17th an abundance of fine ripe 

 seeds. Here then we have a near approach to the 



Gray ' Manual of 13ot. of United States,' 1856, p. 540. 



