Sex expression, skewed sex ratios, and microhabitat distribution in the dioecious desert moss Syntrichia caninervis (Pottiaceae)

Matthew A Bowker, Lloyd R. Stark, D. Nicholas McLetchie, Brent D. Mishler

Research output: Contribution to journalArticle

91 Scopus citations


The moss Syntrichia caninervis is the dominant soil bryophyte in a blackbrush (Coleogyne ramosissima) community in the southern Nevada Mojave Desert, with a mean cover of 6.3%. A survey of the 10-ha study site revealed an expressed ramet sex ratio of 14 ♀ : 1 ♂ (N = 890), with 85% of ramets not expressing sex over their life span, and an expressed population sex ratio of 40 ♀ : 2 ♂: 1 ♀ ♂ (female:male:mixed-sex, N = 89), with 52% of populations not expressing sex. A greater incidence of sex expression was associated with shaded microsites, higher soil moisture content, and taller ramets. Shaded microsites had higher surface soil moisture levels than exposed microsites. In the exposed microhabitat, surface soil moisture was positively correlated with ramet height but not with sex expression. Male ramets and populations were restricted to shaded microhabitats, whereas female ramets and populations were found in both shaded and exposed microhabitats, suggesting gender specialization. The rarity of mature sporophytes, found in 0% of the ramets sampled and in only 3% of the populations, is probably due to the rarity of mixed-sex populations. We hypothesize that mixed-sex populations are rare because of factors relating to male rarity and that the differential cost of sex expression reduces the clonal growth capacity of male individuals.

Original languageEnglish (US)
Pages (from-to)517-526
Number of pages10
JournalAmerican Journal of Botany
Issue number4
StatePublished - 2000
Externally publishedYes



  • Bryophyte
  • Cryptogamic crust
  • Desert
  • Haploid dioecy
  • Ramet
  • Sex expression
  • Sex ratio
  • Sporophyte

ASJC Scopus subject areas

  • Plant Science

Cite this