AROIDEAE 



497 



952. Biarum Schot., and 953. Cryptocoryne Fisch. 



The flower mechanisms of species belonging to these genera resemble that of 

 Nos. 2930 and 2931. 



954. Calla L. 



Protogynous, hermaphrodite fiowers, closely crowded on a fleshy spadix, with 

 a shallow spathe. 



2932. C. palustris L. (Herm. Muller, ' Weit. Beob.,' I, pp. 283-4 ; Warming, 

 ' Smaa bid. o. morfol. Bidrag' ; Engler u. Prantl, ' Araceae,' in ' D. nat. Pflanzenfam.,' 

 II, 4; Knuth, Bot. Centralbl., Cassel, 11, 1892, pp. 289-91, ' Beitrage,' I.) — The 

 large, externally greenish spathe in this species surrounds the short-starsed 

 inflorescence during the bud stage. When 

 it unfolds it is about 3 cm. broad and 4 cm. 

 long, and ends in a cornet-shaped tip almost a 

 cm. long. This large, ovoid plate, white inside 

 with a faint greenish tinge, serves as a ' sign- 

 board.' The conspicuousness is still further 

 increased by the short-stalked spadix, which 

 is about 1-5 cm. long and o-8 mm. in 

 diameter. Herm. Muller describes the 

 flowers as nauseous, on account of their 

 disagreeable odour. 



The flowers are markedly protogynous. 

 The 30-50 stigmas appear in the first stage 

 of anthesis as small, whitish circles, strongly 

 papillose and viscous, on the ovaries. Those 

 of the lower ones are receptive immediately 

 after the opening of the spathe. The anthers 

 only dehisce when some stigmas have shrivelled. 

 In the first stage they are sessile ; in the 

 second they develop short stalks, so that they 

 are raised to the level of the stigmas. Engler 

 points out that the anthers dehisce quite 

 without order, those of flowers situated above 

 and below dehiscing simultaneously, while the 

 stigmas always mature from below upwards, 



and in such a manner that the stigmas of the uppermost flowers and those facing the 

 spathe can be self-pollinated, while the lowest are limited to cross-pollination. 



Visitors. — The following were recorded as stated. — 



Knuth, a few small flies : also (4. 8. '97, in the Kiel Oberrealschule Garden) 

 a young individual of Helix hortensis Z., creeping over the inflorescence. Examination 

 of its foot showed the presence of pollen-grains, and demonstrated the possibility of 

 malacophily in this species. Herm. Muller, numerous small Diptera, e. g. Drosophila 

 graminum Fall., Hydrella griseola isz/A, and species of Chironomus and Tachydromia; 

 also, as casual visitors, a few small beetles — Cassida nobilis Z., Aphthonia caerulea 

 Payk., Meligethes sp., Hypera polygoni L., and Sitona sp. Warming mentions snails 



Kk 



Fig. 413. Calla palustrix, L. (after Herm. 

 Miiller). III. Inflorescence (x i). IV. Single 

 flower in the first (female) stage : the anthers are 

 still closed, the ovary iov) ends in an ovoid one, 

 the truncated end of which forms the stigma {si) ; 

 this is now fresh, greenish in colour, and recep- 

 tive. V. Single flower in the second (male) 

 stage: the stigma {st) has become brown; the 

 anthers are partly ctosed(i2'), partly dehisced and 

 covered with pollen (a-), while one {0") is already 

 empty ; the ovary has swollen so much that zX b b 

 it has become feathered by pressing against the 

 ovaries of adjacent flowers, (x 5.) 



DAVIS. Ill 



