Editing Moss (section)

===Dwarf males===
Moss dwarf males (also known as [[nannandry]] or [[phyllodioicy]]) originate from wind-dispersed male [[spore]]s that settle and germinate on the female shoot where their growth is restricted to a few millimeters. In some species, dwarfness is genetically determined, in that all male spores become dwarf.<ref name="UneKouji">{{Cite journal|url = http://ir.lib.osaka-kyoiku.ac.jp/dspace/handle/123456789/2572|title = Sexual dimorphism in the Japanese species of Macromitrium Brid.(Musci: Orthotrichaceae)|last = Une|first = Kouji|journal = The Journal of the Hattori Botanical Laboratory Devoted to Bryology and Lichenology|pages = 487–513|year = 1985|volume = 59}}</ref> More often, it is environmentally determined in that male spores that land on a female become dwarf, while those that land elsewhere develop into large, female-sized males.<ref name="UneKouji" /><ref>{{Cite journal|title = The male gametophores of Leucobryum glaucum (Hedw.) Ångstr. and L. juniperoideum (Brid.) C. Muell. in two Welsh woodlands|last = Blackstock|first = T. H.|journal = Journal of Bryology|doi = 10.1179/jbr.1987.14.3.535|year = 1987|pages = 535–541|issue = 3|volume = 14| bibcode=1987JBryo..14..535B }}</ref><ref name="Loveland">{{Cite book|title = Sexual dimorphism in the moss genus Dicranum Hedw. (Dissertation)|last = Loveland|first = Hugh Frank|publisher = University of Michigan|year = 1956}}</ref><ref name="Wallace">{{Cite book|title = Developmental morphology and sexual dimorphism in Homalothecium megaptilum (Sull.) Robins. (Dissertation)|last = Wallace|first = M. H.|publisher = Washington State University|year = 1970}}</ref> In the latter case, dwarf males that are transplanted from females to another substrate develop into large shoots, suggesting that the females emit a substance which inhibits the growth of germinating males and possibly also quickens their onset of sexual maturation.<ref name="Loveland" /><ref name="Wallace" /> The nature of such a substance is unknown, but the phytohormone [[auxin]] may be involved<ref name="UneKouji" />

Having the males growing as dwarfs on the female is expected to increase the [[fertilization]] efficiency by minimizing the distance between male and female reproductive organs. Accordingly, it has been observed that fertilization frequency is positively associated with the presence of dwarf males in several [[phyllodioicy|phyllodioicous]] species.<ref>{{Cite journal|title = Studies of fertility of Dicranum majus in two populations with contrasted sporophyte production|last1 = Sagmo Solli|first1 = I. M.|journal = Journal of Bryology|doi =10.1179/jbr.2000.22.1.3 |year =1998 |pages =3–8 |issue =1 |volume = 22|last2 = Söderström|first2 = Lars|last3 = Bakken|first3 = Solveig|last4 = Flatberg|first4 = Kjell Ivar|last5 = Pedersen|first5 = Bård|s2cid = 85349694}}</ref><ref name="Hedenäs">{{Cite journal|title = The overlooked dwarf males in mosses—unique among green land plants|last1 = Hedenäs|first1 = Lars|journal = Perspectives in Plant Ecology, Evolution and Systematics|doi =10.1016/j.ppees.2011.03.001 |year = 2011|pages = 121–135|issue = 2|last2 = Bisang|first2 = Irene|volume = 13| bibcode=2011PPEES..13..121H }}</ref>

Dwarf males occur in several unrelated [[Lineage (evolution)|lineages]]<ref name="Hedenäs" /><ref>{{Cite journal|title = Sex determination in bryophytes|last1 = Ramsay|first1 = Helen P.|journal = Journal of the Hattori Botanical Laboratory|volume = 52|year = 1982|pages = 255–274|last2 = Berrie|first2 = G. K.}}</ref> and may be more common than previously thought.<ref name="Hedenäs" /> For example, it is estimated that between one quarter and half of all [[dioicy|dioicous]] [[pleurocarpous|pleurocarp]]s have dwarf males.<ref name="Hedenäs" />