Smooth goosefoot (Chenopodium subglabrum) COSEWIC assessment and status report: chapter 6

Biology

Little research has been conducted on the biology of C. subglabrum. The most recent study of the species in Flora of North America (FNA editorial committee 2004) focused on the taxonomy. Other research on the species has consisted of habitat surveys (Smith and Bradley 1990; Lamont and Gerry 1998; Schmoller 2002). Some of the information in this section is based on published research (Robson, 1997a, b) and some on recent observations.

Life cycle and reproduction

Chenopodium subglabrum is an annual plant with bisexual flowers (FNA editorial committee 2004). Flowering occurs from June to August and seed production in August and September (Wallis and Wershler 1988). Although no studies on C. subglabrum pollination have been performed, other species in this genus are wind or self-pollinated (Johnson and Ward 1993; Royer and Dickson, 1999). The distance that C. subglabrum pollen travels is unknown. Since the wind-pollinated C. pratericola often occurs in the same habitat with C. subglabrum, hybridization may be possible, although it has not been observed (Bassett and Crompton 1982).

No studies on fecundity, dormancy or germination have been conducted on this species. Lamont and Gerry (1998) asserted that dry weather could limit its persistence or spread. The dramatic increase in the number of individuals observed at most sites in Saskatchewan in 2004 coupled with the observation that the summer was unusually wet and cool suggests that maximum seed germination occurs under moist conditions.

Herbivory

At several sites in Alberta and Saskatchewan there were specimens of C. subglabrum that had been grazed. Grazing may have been by cattle or wildlife. Some grazed plants produced side shoots to compensate for stem loss. A report on the ecology of Ord’s kangaroo rat (a species at risk nationally) noted that there were seeds of C. subglabrum found in their pouches and food caches (Lamont and Gerry 1998).

Physiology

Chenopodium subglabrum is both a halophyte (i.e. salt-loving plant) and a xerophyte (i.e. dry-loving plant). Xerophytes and halophytes are very similar. Halophytes take up as little as possible of soil solutions so that nutrition may not be prejudiced by excess salt in the tissue. Xerophytes must use wisely whatever moisture they can attain, given the dryness of their habitats. Hence, the necessity of checking transpiration for which similar means have been adopted in halophytic and xerophytic plants (Rendle 1967).

Chenopodium subglabrum has seeds that can remain dormant until suitable conditions for germination occur as is typical of several rare annuals in the prairies (Robson 1999). This dormancy can last at least eight years; at the Beaver Creek site plants were observed in 1996 and 2004 but not in the years in between.

Dispersal/migration

The achenes and seeds of C. subglabrum lack structures that would aid in wind (i.e. hairs) or animal (i.e. burs or fleshy fruits) dispersal. The seeds likely fall close to the parent plant. The seeds may be buried by shifting sand after release. This means that the main exchange of genetic material between populations would occur via pollination. The seeds can likely remain dormant for several years, germinating when conditions are suitable (Robson 1999). There may be dormant seeds present in stabilized areas that would germinate if the area were denuded of its vegetative cover.

Interspecific interactions

Plants in the Chenopodiaceae are generally non-mycorrhizal (Mukerji et al. 2000). Since C. subglabrum grows largely in areas of active sand, mycorrhiza are likely not abundant. Several plants observed appeared to be infected by an unidentified purplish fungus that appeared to inhibit growth.

Adaptability

Chenopodium subglabrum has the capability of adapting to changes in climate through its ability to produce seeds that can remain dormant when conditions are unsuitable. It is also adapted to some soil disturbance as plants were observed surrounding several oil wells that had been cleared of vegetation.

Bassett and Crompton (1982) studied C. subglabrum under greenhouse conditions but details regarding the experiment were not given. No attempts to propagate the species for seed production have been attempted.  If seeds were harvested from the wild and grown in a greenhouse the seeds from those plants could be introduced back into the wild. However, given the species’ sensitivity to climate conditions, the seeds may not germinate in the wild the following year making assessment of the introduction success difficult to ascertain.

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