XENOGAMY 43 
The discoverer of Dichogamy (Sprengel, ‘Entd. Geh., p. 19) named the two 
cases of this phenomenon male-female (Androgyna), and female-male (Gynandra). 
These two technical terms cannot, however, be used here, since Linnaeus employed 
them in other connections. Hildebrand, in 1867 (‘Geschlechterverteilung,’ p. 16), 
introduced the expressions Protandry and Protogyny, which would have been 
universally accepted by botanists as being suitable, had not the forms Proterandry and 
Proterogyny, employed by Delpino in 1868 and 1875 (‘ Ulteriori osservazioni,’ i and 
ii), been still more widely adopted. Kirchner, in 1888 (‘Flora von Stuttgart,’ p. 39, 
note), called attention to the fact that Hildebrand’s terms are preferable because shorter 
and more convenient, while grammatically quite as correct as those of Delpino!. 
Dichogamy is by no means limited to individual flowers, for probably all 
monoecious and most dioecious plants are dichogamous. All the former appear 
_to be protogynous, i.e. the female flowers of a plant mature before the male, and this 
time-difference in the development of the sexes often amounts to several days. Thus, 
the female flowers of Alnus viridis are mature four or five days before the male, 
those of Typha minima as much as nine days, while according to Kerner (‘ Nat. 
Hist. Pl.” Eng. Ed. 1, II, p. 313), in the case of alders, birches, elms, oaks, beeches, 
hazels, planes, and the walnut, the difference amounts to two or three days. Accord- 
ing to my own observations, the difference, especially in the case of Corylus avellana, 
may be much greater under certain circumstances. If, in particular, an unfavourable 
rainy or cold period sets in, after the protrusion of the stigmas, the discharge of 
pollen is considerably delayed. 
Most dioecious plants are also protogynous. According to Kerner (op. cit.) 
the female flowers of many willows are mature several days before the male, in 
spite of the fact that the male trees are subject to the same conditions of life as 
the female; they grow in the same ground, are exposed equally to sunlight, and 
encounter the same currents of air. Again, according to Kerner, the stigmas of 
the female flowers of Salix amygdalina are ready for pollination two or three days 
before the anthers of the male flowers dehisce. The same holds for S. purpurea, 
viminalis, and fragilis, while the willows of the lower Alps (S. herbacea, retusa, 
and reticulata) usually present a difference of one day only in the development 
of the two kinds of flowers. In Cannabis sativa, the difference amounts to four 
‘ As these terms will be much used in botanical instruction in secondary schools, efforts have 
been made to find suitable German equivalents for them. W. Behrens in the first edition of 
his ‘Lehrbuch der Allgemeinen Botanik’ spoke of ‘ mannlich-weiblich’ (male-female) (6-9) and 
‘ weiblich-minnlich’ (female-male) (9-4) ways of flowering, thus making use of Sprengel’s original 
terms. [The latter symbol is the long-recognized one for monoecious and is incorrectly introduced in 
the sense of the text by Behrens, and reproduced in the English edition of his textbook.’-—ED.] 
He retained these expressions in his second edition (1882, p. 182), but in the third edition of his 
textbook he introduced ‘vorminnlich’ and ‘vorweiblich’ [i.e. male first and female first], as 
proposed by Hildebrand. E. Nichel (Bot. Centralbl., Cassel, xlix, 1892, pp. 10, 11) suggested the 
terms ‘ pollenvorreif’ or ‘narbennachreif’ [i.e. pollen first ripening or stigma last ripening], and 
‘narbenvorreif’ or ‘ pollennachreif’ [i.e. stigma first ripening or pollen last ripening], and for 
monogamous the term ‘zwitterreif’ [i. e. bisexual ripening]. I would replace these (op. cit., lii, 
pp. 217, 218) by the terms ‘ staubblattvorreif’ and ‘ fruchtblattvorreif’ [i.e. stamen first ripening and 
carpel first ripening], but at the same time maintain that the terms Proterandry and Proterogyny should 
be applied as a matter of course by scientific botanists, and as international terms. [In Britain the 
scientific terms protandry or proterandry and protogyny or proterogyny are in general use.—Eb.] 
