Flora of North America species comparison

Species ca. 15 (3 in the flora).

Sarcocornia is taxonomically difficult and has never been the subject of a taxonomic revision for the Northern Hemisphere. Although it is possible to identify dry specimens to some extent, by comparison, it is impossible to obtain from dried specimens data that can be used in a taxonomic revision. Characters that may be taxonomically useful are lost on drying, especially flower and inflorescence characters and those derived from the fleshy vegetative segments. Habit appears to be useful, but few specimen labels note the habit of the living plant, and the parts collected rarely allow for a reliable determination of habit. Some species, such as S. perennis are prostrate, with the woody stems readily rooting in the substrate. Others such as S. pacifica are procumbent to erect shrubs in which the woody stems usually do not root. This apparently obvious habit difference is sometimes confounded by external factors, erect species becoming procumbent due to water movement, trampling, or burial by silt or sand deposits. Conversely, prostrate rooting species can be disturbed by erosion and appear to be procumbent plants of a nonrooting species.

One of the most useful characters, the indumentum on the testa of the seeds, is rarely present in dried specimens because of the lateness of the plants’ flowering season. Plants collected in August and September rarely have even immature seeds present, so most herbarium specimens do not display this character.

The consequence of these problems is that most accounts of Sarcocornia in North America recognize only one species, frequently using the name Salicornia virginica Linnaeus for the collective entity. The type specimens of S. virginica were collected by John Clayton, presumably from Virginia, which are immature annuals and not flowering. The name S. virginica cannot be applied to a species in this genus.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Genera ca. 100, species ca. 1500 (27 genera, 168 species in the flora).

A number of species introduced from Europe and Asia are weedy in North America. The widespread distribution of the family in the deserts of Eurasia and Australia is indicative of the ancient status of the family. Fossil pollen from this family dates to the Maestrichtian, providing the oldest known fossils in the Caryophylliidae.

Plants in this family typically have Crassulacean Acid Metabolism, have either a C3 or C4 photosynthetic pathway (W. V. Brown 1975; G. W. Welkie and M. Caldwell 1970), accumulate organic acids, free nitrates, and oxalates, and often contain alkaloids. Along with other members of the Caryophyllales, members of the family contain pigments called betalains (named for the genus Beta) rather than anthocyanins.

Economically important members of this family include spinach and chard (Spinacia oleracea) and beets (Beta vulgaris). Seeds in this family generally provide a rich source of protein, and one species, Chenopodium quinoa, is gaining widespread acceptance as a cereal crop. Toxicity from high levels of nitrates or oxalates has been reported for a number of species (J. M. Kingsbury 1964), and the pollen is known to be allergenic (T. C. Fuller and E. McClintock 1986). The nutritional characteristics of many species that we share with northern Asia were described by M. M. Iljin (1936).

Molecular and morphologic studies provide evidence supporting the inclusion of the Chenopodiaceae within Amaranthaceae (Angiosperm Phylogeny Group 1998; W. S. Judd and I. K. Ferguson 1999; J. E. Rodman 1990). However, until discordant elements within these lineages, such as Sarcobatus (H.-D. Behnke 1997), are interpreted within a larger evolutionary scheme, the disposition of family groups remains problematic.

(Discussion copyrighted by Flora of North America; reprinted with permission.)