5i8 ANGIOSPERMAE—MONOCOTYLEDONES 



976. Zea L. 



2985. Z. Mays L. {C/. G. Krafft, ' D. norm. u. anorm. Metamorph. d. Maispfl.,' 

 1870.) — Hildebrand (' Bestaubungsverh. d. Gramineen') says that the terminal male 

 panicle of this species has already dehisced when the stigmas of the lateral female 

 spikes diverge ; Kemer ('Nat. Hist. PI.,' Eng. Ed. i, II, p. 313) describes the species 

 as protog)'nous. I can confirm Hildebrand's statements from observations of culti- 

 vated plants in the Oberrealschule Garden in Kiel. 



Warnstorf describes the maize as protandrous to homogamous. The anthers 

 dehisce apically only by a short, lateral slit. The pollen-grains are sulphur-yellow in 

 colour, resembling a short, blunt pyramid with a rounded base, very large, up to 

 100 /i long and 70 /a broad. Female flowers are not infrequently found in the male 

 panicle, and male spikelets in the female spike. 



Kirchner ('Flora v. Stuttgart,' p. 115) states that the dehiscence of the anthers 

 continues until the stigmas mature, so that crossing is favoured at first, and geitono- 

 gamy may take place later. 



Hildebrand ('D. Geschlechts-Vert. b. d. Pfl.,' p. 10) says that single female 

 flowers sometimes occur on the male inflorescences, more frequently the female 

 inflorescences end in a male spike. Penzig (' Studi morfol.,' I) gives a similar account ; 

 he often observed female spikelets in the male panicle and male spikelets in the 

 female spikes, besides hermaphrodite flowers and stamens transformed into carpels. 

 Krafft (op. cit.) describes a number of such variations. 



The plants cultivated in gardens in Kiel are markedly protandrous, the male 

 flowers arranged in terminal panicles dehiscing before the stigmas of female flowers 

 on the same plant protrude, but (perhaps only in very sheltered stations) enough 

 pollen-grains remaining over to fertilize the later projecting stigmas of the same plant 

 by fall of pollen. This is proved by the fact that a single plant which grew up 

 spontaneously in my garden set abundant fertile fruits, although no other maize-plant 

 grew for a considerable distance round. The species is therefore self-fertile, but only 

 imperfectly so, perhaps from scarcity of pollen ; each of the two female spikes of the 

 plant contained about 630 ovules, of which in the older one only 103 (16 %) and in 

 the younger only 25 (4%) fertile fruits were set. The male flowers possess (like 

 many grasses) an odour of cumarin ; the female ones are odourless (Knuth, ' Bliiten- 

 biol. Notizen '). 



977. Andropogon L. 



2986. A. Ischaemum L. (Kirchner, ' Beitrage,' p. 71.) — In plants of this 

 species growing in the Hohenheim Botanic Garden there are always two spikelets, 

 each consisting of one flower, which are situated together at the same level on the 

 spicate part of the inflorescence, of which one is sessile and hermaphrodite and the 

 other stalked and male. All the sessile (hermaphrodite) spikelets on the inflorescences 

 now mature simultaneously, and after they have faded all the stalked (male) spikelets, 

 again simultaneously. The whole inflorescence is therefore hermaphrodite at first, 

 and purely male later. The hermaphrodite flowers are homogamous ; their dark-red 

 stigmas are in the form of a cylindrical brush. All the anthers are black-red and 

 attached to thin, limp filaments. 



