478 ANGIOSPERMAEMONOCOTYLEDONES 



sometimes being only a few hours (Juncus tenuis Willd., J. filiformisZ., J. Chamissoni; 

 Kunth, J. balticus Willd.), generally one day, but may extiend over nine days or perhaps 

 more (Luzula campestris DC). 



Each flower opens only once. Buchenau (' Monographia/ p. 41, ' Bestaubungs- 

 verh.,' p. 372) says that the opening depends on a usually very temporary turgescence of 

 the floral receptacle, the bases of the filaments, and the inner surface of the perianth 

 leaves, the swelling being shared very unequally by these organs in different species. 



All species of Juncaceae do not bear inconspicuous flowers, for a large number 

 possess brilliantly coloured ones. Buchenau enumerates 4 1 such species (' Bestau- 

 bungsverh.,' pp. 373-4), and these are therefore probably entomophilous, as they 

 form abundant masses of pollen and are well adapted to attract insects by the 

 brightly-coloured, shining, juicy cells at the base of the flower (pseudo-nectaries). 



Luzula lutea DC. and L. nivea DC. are almost the only ones of our Central 

 European species possessing a brightly coloured perianth, and they are visited by 

 insects. In Graubunden Hermann Muller (' Alpenblumen,' pp. 38-9) saw the 

 former visited by a po-cltg. humble-bee and a po-dvg. hover-fly; a hawk-moth 

 (Zygaena) rested idly on the flowers. At Chur he frequently saw Luzula nivea DC. 

 visited by a flower-beetle (anthobium). 



Buchenau (' Bestaubungsverh.,' pp. 378-9) gives the following account of the 

 flower mechanisms actually occurring among Juncaceae. 



I. Autogamy. Fertilization of the flower with its own pollen certainl; 

 takes place very frequently and effectively. 



(a) Cleisiogamous Flowers, usually also cryptantherous, Apparent exclusively in 

 Juncus homalocaulis F. Muell., perhaps also in J. repens Michx. and J. setaceus Rostk. ;| 

 associated with chasmogamy in J. bufonius Z., J. capitatus Weigel, J. pygmaeus Rich.{i 

 J. Chamissonis Kunth, J. capillaceus Lam., Luzula purpurea Link, and probabl 

 other species also. 



(b) Chasmogamous Flowers. 

 (i) Those with stigmas and anthers ver}' near together (flowers often ope 



but little) : Juncus tenuis Willd., J. Chamissonis Kunth, J. pygmaeus Rich., J. t: 

 glumis L., Luzula purpurea Link, Prionium Palmita E. Mey. 



(2) Those in which the stigmas are still receptive when the perianth closes, 

 then come into contact with the pollen-grains of the same flower strewn on the 

 perianth leaves : species of Luzula. 



- (3) Those with stigmas and anthers not very near each other, in which during 

 the hermaphrodite stage pollen reaches the stigma of the same flower when the 

 anthers dehisce, or by means of the wind or of being shaken : numerous species. 



II. Geitonogamy, more rarely Xenogamy. These can, of course, only 

 occur in chasmogamous flowers, and are greatly assisted by protogyny (more or 

 less marked). Geitonogamy is necessary in the case of Luzula campestris DC. 

 (and L. spadicea DC. (?)), where in consequence of complete heterogamy the flowers 

 are first female, then neuter, and finally male. 



(a) Anemophily. Pollen is transferred to the stigmas of adjacent flowers by 

 means of the wind or mechanical shaking acting in the same way ; this certainly 



