Why are Syntrichia caninervis sporophytes rare?
In the production of sporophytes there are two steps to consider. First, the female needs to be fertilized by the male. Second, a fertilized female must be able support the sporophyte to maturity. Fertilization needs water to carry sperm from the male to the female plant and water is rare in the Mojave Desert. In bryophytes, especially soil bryophytes, maximum possible fertilization distances are typically short. For a good chance of fertilization a male Syntrichia caninervis plant has to be within about a centimetre of a female plant. Given the high proportion of female plants noted above, it’s fairly easy to see that most females will not be close enough to a male plant. Moreover, it has been estimated that perhaps only 10% of the Syntrichia plants produce sex organs during their lives. If, despite those obstacles, a female plant is fertilized, it faces the further stress of bearing the sporophyte to maturity. In the previous section you saw that in producing the perigonia the males
