DISTRIBUTION OF SEXES. 295 



develop imperfect flowers, which are liable to be mistaken at first sight for truly 

 hermaphrodite. They have plain well-developed ovaries, and stamens in whose 

 anthers pollen-grains are formed in greater or less numbers; but experiments with 

 this pollen have shown that when deposited on the stigma it emits no pollen-tubes, 

 and consequently the flowers are not in reality truly hermaphrodite, but only 

 apparently so. This is the case in some of the flowers in the panicle of the Horse 

 Chestnuts {JEscwlus and Pavia), in some species of Dock (Rumex alpinus, obtusi- 

 folius, &c.), and in some of the flowers in the centre of the heads of the Colt's-foot, 

 Marigold, and Butter-bur (Tussilago, Calendula, Petasites). They appear herma- 

 phrodite although the ovaries never form fruits with fertile seeds, because their 

 stigmas are not capable of inciting the emission of pollen-tubes in the ripe pollen 

 deposited on them. Again, there are many plants where either the ovaries or the 

 stamens are so reduced that they can only be discovered by careful searching. 

 Some examples of the red Campion (Lychnis diurna) have flowers with well- 

 developed ovaries and stigmas, which are capable of fertilization, while their 

 stamens are extremely minute, consisting of triangular bodies scarcely 1 mm. long, 

 which bear a small polished head destitute of pollen instead of an anther. Other 

 plants of this same Campion bear flowers with ten stamens whose long ribbon-like 

 filaments are surmounted by large anthers with fertile pollen, but instead of the 

 ovary there is only a minute knob with two points indicating the stigma. The 

 same thing occurs in the flowers of some Valerians ( Valeriana dioica, sirnplici folia, 

 &c.). The racemes of the Sycamore {Acer Pseudo-platanus) exhibit every imagin- 

 able gradation from pseudo-hermaphrodite male flowers, with comparatively large 

 ovaries, to those in which the ovaries are reduced or altogether absent. I have 

 mentioned these instances, to which many others might be added, to show that 

 there is no lack of transitional forms between pseudo- hermaphrodite and truly 

 pistillate and staminate flowers; and again, in plants with neuter flowers, especially 

 in many species of the Grape-Hyacinth (Muscari), we have gradations from truly- 

 hermaphrodite to neuter flowers. The remarkable structures known as gall-flowers 

 (cf. pp. 159, 160) may also be mentioned here. They represent neuter flowers, and 

 occasionally undoubted links are found between them and true pistillate flowers. 

 In spite of these transitional forms, which to some extent break down the limits 

 between the various kinds of flower, it is advisable to retain the names already used 

 for the separate forms, since otherwise it would be impossible to give a general 

 account of the arrangement of the sexes in Phanerogams. 



It has been stated above that botanists were formerly content with dividing 

 plants according to their sex into those with hermaphrodite, monoecious, dioecious, 

 and polygamous flowers (cf. p. 291). This classification, however, is no longer 

 adequate to the present standpoint of our knowledge. I will now attempt to give 

 an approximate account of the extremely complex conditions which must be con- 

 sidered in this matter, but will keep to the old divisions as far as possible in so 

 doing. 



We may place in the first group those pknts whose species develop true herma- 



