CYPERACEAE 515 



(6) Female spikelets provided at the base with lateral spikelets, which may be 

 either purely female, or else male at the tip. 



2982. C. panicea L. — This species is homogamous; the pollen-grains are 

 pale-yellow in colour, tetrahedral, smooth, about 37 ju, in diameter. Warnstorf 

 observed the following variations in the inflorescences of this species at Ruppin : — 



(i) Two or three female spikes are crowded closely together immediately below 

 the terminal male spike, and one female spike is situated about 3-5 cm. deeper. 



(2) One thick, ovoid, crowded female spike is situated at the tip of the stem, and 

 one purely male or partly female on one slightly lower ; 



(3) One ovoid, crowded female spike is situated below the terminal male spike. 



Warnstorf also saw a very robust variety, 40-50 cm. high, around and in moor- 

 pools not far from Lindow. It bore one very dense clavate terminal male spikelet, 

 and several normal female spikes. The plant gives the impression of being quite 

 foreign by the form of the male spikes and the breadth of the leaves. 



2983. C. sylvatica Huds. — This species frequently occurs with compound 

 spikelets. 



2984. C. Pseudo-cyperus L. — In this species also numerous variations in the 

 distribution of the sexes are found, and Appel in particular often observed spikelets 

 which were male at the base and female at the tip. 



CXXV. ORDER GRAMINEAE JUSS. 



Cf. Kornicke, 'D. Arten u. Varietaten d. Getreides,' 1885, a memoir omitted 

 from the bibliography. 



All species of this order are distinctly anemophilous. The flowers of grasses 

 are, as De CandoUe observed, ephemeral, opening only once ; this usually takes place 

 in the morning during favourable weather. The opening of the flowers, caused by 

 the divergence of the glumes, is effected by the two lodicules, according to Hackel 

 (Bot. Ztg., Leipzig, xxxviii, 1880, pp. 432-7). These become fleshy and succulent, 

 and usually spheroidally swollen at the base, by which means they overcome the 

 resistance of the elastic outer glume and move it outwards. After fading, which 

 occurs at the latest in 1-2 hours, the lodicules shrivel up again into small thin leaves, 

 thus bringing the outer glume once more into its former position. This is particularly 

 plain in Arrhenatherum elatius Mert. el Koch. Turgidity increases very quickly as 

 the flower opens, and may therefore be traced to the absorption of water ; a pin-prick 

 actually causes a small drop to exude. 



Rimpau (Landw. Jahrb., Berlin, xii, 1883, pp. 875-919) has carefully investigated 

 the flowering of cereals. He confirms the fact first pointed out by Hackel, that the 

 opening of the glumes is affected by the swelling of the lodicules. The rapid growth 

 of the filaments on the opening of the flowers in many species, first observed by 

 Askenasy, is also confirmed by Rimpau. 



Hackel (' Gramineae,' in Engler u. Prantl's 'D. nat. Pflanzenfam.,' II, 2) states 

 that grasses are usually protandrous, more rarely protogynous (Alopecurus, Antho- 



l1 2 



