CLEISTOGAMY 51 
algerica (Battandier, Bul. soc. bot., Paris, xxx), Brassica nigra (Todd, Amer. Nat., 
Boston, xv, 1881), Erythraea Centaurium (A. S. Wilson, Brit. Ass. Rep., 1878), and 
Anchusa officinalis (E. Warming, Bot. Tids., Kjobenhavn, xvii, 1877). I myself 
always found the last three species homostylous, 
VI. Cleistogamy!’. 
Hugo von Mohl in his memoir, ‘ Einige Beobachtungen tiber dimorphe Bliiten ’ 
(Bot. Ztg., Leipzig, xxi, 1863, pp. 309 et seq.), mentions a number of plants bearing 
on the same stock some flowers that open normally and also others that do not 
open at all. The corolla of such flowers is reduced or absent, while stamens and 
pistil are in some respects well developed. Healthy fruits result from the self- 
fertilization that takes place in the permanently closed bud-like flowers. A few 
years later Kuhn (Bot. Ztg., xxv, 1867, pp. 65-7) published a further and exten- 
sive list of such plants, and introduced the term cledsfogamous to designate the 
permanently closed flowers. 
According to H. v. Mohl (Bot. Ztg., xxi, 1863), Dillenius was probably the 
first to discover cleistogamous flowers on the plant subsequently named Ruellia 
clandestina by Linnaeus (Hort. Eltham., 1732, p. 328, Fig. 320). Viola mirabilis 
was the second plant in which Dillenius observed this phenomenon: he found 
that the spring-flowers with well-developed corolla and fully formed reproductive 
organs rarely produce fruit, while the later flowers devoid of corolla do so regularly. 
In many parts of his writings Linnaeus speaks of cleistogamous flowers, and proves 
that in these small blossoms the want of stamens and carpels is only apparent. 
Our knowledge of cleistogamous flowers was further extended by the observa- 
tions of:—Schkuhr, Hegetschweiler, De Candolle, Du Petit Thouars, L. C. 
Richard, Adrien de Jussieu, Aug. St. Hilaire, Bentham, Torrey and Asa Gray, 
Spach, Weinmann, Wight, Weddell, Maximowicz, Daniel Miiller, Brongniart, 
Michalet, and others. H. v. Mohl’s (op. cit., pp. 321-8) researches finally gave us 
a clear view of these remarkable flowers. 
Hugo von Mohl’s classical account of the cleistogamous flowers of Oxalis 
Acetosella (Bot. Ztg., 1863, pp. 321, 322) is somewhat as follows. In the second 
week of June, when the fruits of the spring-flowers possessing corollas contained 
ripe seeds (at Tiibingen), there were large numbers of small flowers in all stages 
of development up to the complete maturation of fruit. They usually occurred 
on plants which had developed one or several spring-flowers in the axils of the upper 
leaves, but were also occasionally present on plants devoid of spring-flowers. These 
summer-flowers and fruits are distinguished very easily from the spring-flowers by 
the different length and direction of the flower-stalk. The stalk of the spring-fruit 
has a length of about three inches, is straight, and possesses a joint bearing two 
bracteoles, about half-way down. The peduncle of the small flower, on the other 
hand, is only about four lines long (1’”= about 22 mm.), and bent like a hook 
at the top, while its joint is. only 2-1 line from the flower. The latter, owing 
to the shortness of the flower-stalk, is hidden in the moss and pine-needles among 
1 [See K. Goebel, ‘Die kleistogamen Bliiten und die Anpassungstheorie,’ Biol. Centralbl., 
Berlin, xxiv, 1904, for the most recent exposition of cleistogamy.—ED. ] 
E 2 
