PLANT AGIN ACE AE 327 



Herm. Miiller (Alps), a humble-bee, a hover-fly (Melanostoma mellina Z.), 



3 Lepidoptera, and an earwig larva (Forficula). Loew (Switzerland), the hover-fly 

 Didea intermedia Loew, po-dvg. 



2397. P' serpentina Vill. (= P. maritima Z., according to the Index 

 Kewensts). This species agrees with the preceding one, but all its parts are larger. 



2398. P. maritima L. (Knuth, ' Bl. u. Insekt. a. d. nordfr. Ins.,' pp. 125-6 ; 

 Schulz, 'Beitrage,' II, p. 198.) In this species the stigma projects from the bud, 

 persists throughout the maturation of the stamens, and was still receptive after the 

 anthers had faded in plants which I examined in the North Frisian Islands. Schulz 

 observed gynomonoecism and gynodioecism, generally 5-10 %, rarely up to 20 %. 



2399. P. Coronopus L. (Knuth, 'Bl. u. Insekt. a. d. nordfr. Ins.,' p. 125 ; 

 Ludwig, ' Lehrbuch d. Biol. d. Pfl.') This species, again, is strongly protogynous with 

 persistent stigmas in the North Frisian Islands. Ludwig observed transitions to 

 gynodioecism, and also found heteranthery, i.e. two kinds of anthers, resembling 

 those in P. major. 



2400. P. borealis L. Warming describes this species as anemophilous. 



2401. P. arenaria Waldst. et Kit. (Kirchner, ' Beitrage,' p. 58 ; Knuth, 

 ' Bloemenbiol. Bijdragen.') The flower mechanism in cultivated plants of this species 

 agrees essentially with that of hermaphrodite 



flowers of P. lanceolata. In the first stage the 

 filiform red stigma projects 3 mm. from the 

 closed bud-like flower, while the anthers, on 

 short filaments, are situated at its base. Later 

 on the calyx opens, the inconspicuous corolla 

 unfolds, and the dehiscing anthers project 



4 mm. from the flower, borne on the fully- ^io.z^?,.Pianiago maritima, l. {from 



^ ' ' nature), (i) Flower in the first female stage; 



elongated filaments, which are much attenuated the already receptive stigma is projecting 



, _,, . . r J J from the still apposed corolla-lobes. (2) Do. 



above. 1 he stigma is now taaed. in the hermaphrodite stage ; the stamens with 



IT- ^r .1 /T7-' 1 T) i /- J \ 'heir dehiscing anthers project as well as 



Visitors. Knuth (Kiel Botanic Garden) the papillose stigma. (3) Do. in the second 

 saw the hover-fly Melanostoma mellina Z., f^'"^'^ ^'^^^ : ''^ ^t'" receptive stigma pro. 



' jects, as well as a filament which has lost its 



po-dvg. anther ; the corolla- lobes are reflexed. 



2402. P. Cynops L. (Kirchner, ' Beitrage,' pp. 58-9.) The flower mechanism 

 of this species is the same as that of P. arenaria. In the first (female) stage the 

 stigma projects 4 mm. from the flower, and in the second (male) stage the anthers 

 protrude 8 mm. 



2403. P. Lagopus L. (Ludwig, Bot. Centralbl., Cassel, iii, 1880, p. 829.) 

 Ludwig describes this species as gynodioecious. 



2404. P. virginica L. (Ludwig, op. cit., iii, pp. 862-3.) Ludwig describes 

 cultivated plants of this species as possessing cleistogamous flowers. 



