CHENOPODIACEAE 337 



are adapted for insect pollination, as anthesis lasts for weeks, giving ample oppor- 

 tunity for insect-visits. 



2448. A. littoralis L. (Knuth, 'Bl. u. Insekt. a. d. Halligen.') — This species 

 is probably anemophilous, but occasionally pollinated by means of insects. Volkens 

 (op. cit.) is of opinion that species of Atriplex are entomophilous, because anthesis 

 extends over several weeks. My observations showed insect-visits to be extremely 

 few, as might be expected from the inconspicuousness of the flowers. 



Visitors. — Knuth (Kiel Harbour) observed the hover-fly Syrphus balteatus Deg., 

 po-dvg. 



2449. A. hastata L. (Knuth, op. cit.) — This species agrees with A. littoralis. 



2450. A. portulacoides L. (= Obione portulacoides Moq.). (Knuth, op. cit.) 

 — This species is perhaps anemophilous. 



2451. A. pedunculata L. (= Obione pedunculata Moj.). — As the last species. 



LXXXVIII. ORDER POLYGONACEAE JUSS. 



Literature. — Knuth, ' Bl. u. Insekt. a. d. nordfr. Ins.,' p. 127, ' Grundriss d. 

 Blutenbiol.,' p. 88. 



Flowers generally hermaphrodite, possessing a petaloid perianth that serves to 

 attract insects. Their crowding into spicate or paniculate inflorescences increases 

 their conspicuousness. The number and frequency of visits is proportionate to the 

 size of these and the amount of nectar secreted. The probability of cross-pollination 

 increases accordingly and the importance of automatic self-pollination is lessened. 

 Many species are dimorphous. 



763. Rumex L 



Flowers hermaphrodite, dioecious, or polygamous ; protandrous, homogamous, 

 or protogynous ; anemophilous, but receiving occasional insect-visits. Filaments and 

 flower-stalk generally flexible. Stigma penicillate. Geitonogamy is possible, the 

 flowers being usually arranged in dense panicles. 



Haussknecht asserts that hybridization by means of the wind may be easily 

 effected in consequence of the close association of diff"erent species. 



Hermann Miiller observed in the Alps that the fiery-red fruits of Rumex species 

 frequently attracted butterflies (sp. of Polyommatus and Argynnis) of similar colour, 

 which settled on them for a considerable time (' Alpenblumen,' p. 182). 



2452. R. crispus L. (Axell, ' Om Anord. for Fanerog. Vaxt. Befrukt.,' p. 57 ; 

 Schulz, 'Beitrage,' II, p. 155; Kirchner, ' Flora v. Stuttgart,' p. 209.) — This species 

 bears protandrous wind flowers, sometimes gynomonoecious or androdioecious ; the 

 female are smaller than the hermaphrodite ones. Schulz says that the stigmatic 

 branches of the latter are hidden between the leaves of the perianth when the anthers 

 dehisce, so that in consequence of the pendulous position of the flower autogamy is 

 prevented. When the anthers have dropped off", the three stigmatic branches project 

 freely. The female flowers contain vestiges of six stamens. Occasionally some of 

 the stamens are reduced in the hermaphrodite flowers. 



