The Genetics of Garden Plants (1947) p. 42
Morley Benjamin Crane, William John Cooper Lawrence

Haploid Parthenogenesis

Another exceptional form of reproduction where fusion of the male pollen nucleus and the female egg-cell nucleus does not take place occasionally occurs in plants. In these cases a haploid nucleus develops into a new embryo which gives rise to a haploid plant with only one set of chromosomes. This abnormal mode of reproduction called "parthenogenesis" has been described in Datura, Solanum, Campanula, Oenothera and several other plants. Haploid plants are much smaller than their diploid parents and are generally sterile.

The above are examples of female parthenogenesis; a few cases of male parthenogenesis have also been recorded. In these cases the nucleus of the male parent develops into an embryo within the ostensible female parent, without fertilisation or fusion with the female nucleus. It has been reported in the strawberry, Nicotiana, Vicia saliva and Euchlaena mexicana. In Nicotiana the offspring had the reduced (n) chromosome number of the male parent, but in the strawberry, Vicia and Euchlaena the offspring had the 2n number of the male parent, presumably as a result of subsequent chromosome doubling, or the function of an unreduced germ-cell. Thus Ichijima (1928), from crossing Fragaria vesca (2n = 14) with Fragaria virginiana (2n = 56), obtained a plant with fifty-six chromosomes. Bleier (1929), from crosses between Lens esculenta (2n = 14) and Vicia sativa (2n = 12), found a proportion of the offspring to be Vicia sativa with twelve chromosomes, and apparently this frequently happens in Vicia following natural cross-fertilisation.