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 ook. e¢ 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, ‘Einftihrung 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 staiks 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. Hoffmann (‘Kulturversuche iiber Variation,’ 
Bot. Ztg., xli, 1883) with cleistogamous flowers gave as a result for Lamium amplexi- 
caule that the offspring were only partly cleistogamous, and this was specially the 
case after close sowing. In Hordeum vulgare Z. 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 S% A. and Janusia A. /uss. (Jussieu), Aspicarpa 
urens Rich. (H. v. Mohl), Gaudichaudia H. 2. XK. (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 Kerner (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 ozss. (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 Anze., hirsuta Zag., gallica Z., cerastoides Z.., 
tridentata Desf, clandestina /Jacg., longicaulis Pourr., apetala W., inaperta Z., an- 
tirrhina Z. (all by Batalin). 
