58 INTRODUCTION 



papillae. So that flowers originally adapted to the visits of insects are now 

 modified by the closing of the ingress, only self-fertilization takes place, and 

 chasmogamous forms are wanting (?). 



Burck (op. cit., viii, 1890, pp. 122-62) has subsequently discovered other 

 similar cases of perfectly closed, but otherwise normally formed flowers in Anonaceae ; 

 as, for example, Unona coelophlaea Scheff, and others, Artabotrys suaveolens, A.Blumei, 

 Goniothalamus giganteus Hook, et Th., and Cyathocalyx zeylanica. From their 

 occurrence he draws the inference that Nature has altered her original plan of 

 cross-fertilization, owing to subsequent modifications in the conditions of life of 

 the species in question, and has gradually adapted them to self-fertilization 

 exclusively. The closing of the flowers is possibly to be explained as an 

 adaptation for protection against ants (according to Loew, ' Einfiihrung in die 

 Bliitenbiologie,' p. 311, note). 



According to Koehne, Ammannia latifolia is also exclusively cleistogamous. 

 For such flowers the term archo-cleistogamous might be introduced. 



Many cleistogamous flowers bend their stalks in such a way that the fruits 

 which develop are buried in the earth. Excellent protection is thus afforded to 

 the seeds, but their dispersal is seriously prejudiced. Such phenomena are known 

 in species belonging to the genera Amphicarpaea, Commelina, Linaria, Oxalis, 

 Vandellia, Vicia, Viola, Voandzeia, and also in Cardamine chenopodifolia Pers. 

 (Grisebach). 



The culture experiments made by H. Hoff'mann ('Kulturversuche iiber Variation,' 

 Bot. Ztg., xli, 1883) with cleistogamous flowers gave as a result for Lamium amplexi- 

 caule that the off"spring were only partly cleistogamous, and this was specially the 

 case after close sowing. In Hordeum vulgare L. var. nudum, almost all the flowers 

 that were raised throughout a decade were cleistogamous. 



Besides those already named, the following plants have from time to time been 

 recognized as examples of true cleistogamy : 



Cruciferae : Subularia aquatica (Hiltner), Thlaspi arvense (Hieronymus). 



Malpighiaceae : Camarea St. Hil. and Janusia A. Juss. (Jussieu), Aspicarpa 

 urens Rich. (H. v. Mohl), Gaudichaudia H. B. K. (Kuhn). 



Violaceae: Viola mirabilis (Dillenius, 1732 ; Linnaeus, 1749), V. nana (Darwin), 

 V. Roxburghiana (Darwin), V. stagnina (H. Miiller), V. sylvatica (Corry and Bennett), 

 V. arenaria (Kerner), V. canina (Kerner), V. hirta var. Salvatoriana n. f. (Calloni), 

 V. sepincola Kerjier (Kerner), V. sciaphila (Calloni), V. elatior (H. v. Mohl), 

 V. biflora, V. of the Campos of St. Catharina (Fr. Miiller), V. cucullata, floribunda, 

 and sagittata (Bennett), V. sarmentosa Dougl. (Meehan), V. suberosa (Battandier), 

 V. filicaulis and Cunninghamii (G. M. Thompson). 



Cistaceae : Helianthemum guttatum (Linnaeus, Ascherson), H. kahiricum Del., 

 Lippii Pers. var. micranthum Boiss. (ditto). 



Droseraceae : Drosera anglica (Darwin), D. rotundifolia (Knuth), D. intermedia 

 (Knuth), Aldrovandia vesiculosa (Bentham and Hooker, Korczinski). 



Polygalaceae : Species of Polygala (Darwin). 



Silenaceae : Silene vilipensa Knze., hirsuta Lag., gallica Z., cerastoides Z., 

 tridentata Des/., clandestina Jacq., longicaulis Pourr.^ apetala W.., inaperta Z., an- 

 tirrhina Z. (all by Batalin). 



