Bryophytes

Bryology, as defined by Webster’s dictionary, is a branch of botany that deals with [study of] the bryophytes.  The term “bryophyte” originated from the Greek language and refers to “plants that swell upon hydration.” 

This ability to swell when wetted certainly hints at the capability of these organisms to resume their former stature following desiccation, a key feature in the physiological ecology of bryophytes.  Frequently viewed as “poor relatives” of the more flashy angiosperms or as the “lower plants,” these characterizations no doubt allude to their early evolutionary emergence.  Bryophytes are often lumped into a loose collection of organisms referred to as cryptogams.  The cryptogams (kryptos, meaning hidden and gameein, meaning to marry) are a disparate assemblage of organisms such as algae, lichens, fungi, and ferns, most of which are at best remotely related to the other members of the artificial group.  As such, this term is largely obsolete in contemporary plant systematics, although it does illustrate the overlooked status of these organisms. 

Bryophytes, in the traditional sense, include the Bryophyta (mosses), Marchantiophyta (liverworts), and Anthocerotophyta (hornworts).

All of these groups are non-vascular plants with similar habits, and which frequently occupy the same habitats.  Although regularly consolidated into a single group, based on an overall lack of complexity and similar life cycle strategies, these groups have very little in common and likely reflect differing ancestral lineages.  As non-vascular plants, bryophytes are generally thought of as the first land plants.  Mishler et al. (1994) concluded the Charophyceae, one of four basal algal lineages, are the ancestor of all extant land plants to include the bryophytes and tracheophytes.  However, the placement of the bryophyte groups within this basal lineage has not yet reached a final consensus.  Summarizing relationships among the bryophytes relative to their ancestors (charophytes) and their descendants (tracheophytes), suggests the convergence of hypotheses place the hornworts as the most basal group, with the mosses and liverworts in a monophyletic group sister to the tracheophytes.

Bryophytes as a group consist of between 15,000 and 25,000 species worldwide and are the second largest group of plants.

They occur on every continent, and in every habitat, where vascular plants reside.  In fact, bryophytes are the dominant plants, in species diversity and biomass, in a number of regions in the world.  On the continent of Antarctica, only three species of vascular plants are known to persist, Deschampsia antarctica Desvaux (Antarctic hairgrass), Poa annua Linnaeus (annual bluegrass), and Colobanthus quitensis (Kunth) Bartling (Antarctic pearlwort), the remaining flora consists of mosses and liverworts.  In the higher latitudes of arctic tundra ecosystems, species richness declines in both vascular and non-vascular plants.  However the decrease in the bryophytes is much less than that of vascular plants which leads to an increase in the relative abundance of bryophytes.  Longton (1982) suggested bryophytes are highly significant in terms of cover, richness, biomass, and production in polar ecosystems; and Rozzi et al. (2008) demonstrate an inversion between vascular and non-vascular plant diversity in the sub-Antarctic Magellanic region of southwestern South America.  Clearly this distinction does not apply in any ecoregion in Texas.  However, only minimal investigation into the diversity and ecology of bryophytes in the state, and region, has been completed.