partially inbred nature: narrower genetic base, lower vigor andfiber quantity,
slower breeding improvement, combined with the need to maintain the monoecious
population in strict isolation during seed multiplication, because of lower com-
petitiveness of monoecious pollen compared to contaminating dioecious male
individuals (Bocsa and Karus 1998 ).
Sex, and particularly the expression of monoecy, is a relativelyflexible trait in
C. sativa. Anomalies inflower development are often observed in dioecious hemp,
with the appearance of mixed inflorescences with male and femaleflowers or even
hermaphroditeflowers bearing both anthers and carpels. In addition, it has been
demonstrated that theCannabisplant is able to“switch”from the formation of male
flowers to femaleflowers (or vice versa) upon changes in environmental conditions
or following specific chemical treatments (Mohan Ram and Sett1982a,b; Mohan
Ram and Jaiswal 1970 ); the ploidy level also can influence the expression of sex.
Thisflexibility has been exploited for the constitution of inbred lines, employed for
genetic studies (de Meijer et al. 2003 ; Weiblen et al. 2015 ) or for production
purposes, especially in the pharmaceutical industry. As for monoecy, in the absence
of strict selection, dioecious male plants occur at increasing rates from one
Fig. 15.1 Female (a), male (b) and monoecious (c)inflorescences ofCannabis sativa.dMADC2
sequence-based marker useful for the identification of sex in dioecious plants.Mmale plants;
Ffemale plants;Hmonoecious plants. Female and monoecious plants cannot be distinguished
15 Genomics and Molecular Markers inCannabis sativaL. 327