Showy phlox (Phlox speciosa): COSEWIC assessment and status report: chapter 3

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Species Information

Name and classification

The genus Phlox is a member of the family Polemoniaceae. The genus occurs in North America and northern Asia, but the greatest number of species is found in western North America. There are 68 species of Phlox in North America, with 16 species found in Canada and 6 in British Columbia (Douglas et al. 1999). Currently, there are no known taxonomic problems or uncertainties associated with Phloxspeciosa ssp. occidentalis. The taxon has not been subject to taxonomic or nomenclatural changes in recent history. Since the only subspecies that is found in Canada is ssp. occidentalis (Douglas et al. 1999), the Canadian plants are referred to, in this report, as Phloxspeciosa (except where greater precision is required to delimit the range of this taxon).  Five other subspecies are found in the western United States.

Description

Phlox speciosa is illustrated in Figure 1. It is a perennial herb with a somewhat shrubby base. Stems are erect, 15-40 cm tall, rising from a woody taproot. The plant is glandular to glandular-hairy above, and hairy below. The opposite leaves are linear to lanceolate, to 7 cm long and 1 cm wide, with well-developed internodes. The inflorescence consists of loose, leafy-bracted, terminal clusters of stalked flowers. Corollas range from pink to white. The corolla tube (1-1.5 cm long) spreads to five wide lobes (1-1.5 cm long) that are notched at the tip. Calyces are glandular, with flat, transparent segments between the five green ribs. Styles range from 0.5-2 mm long (description based on ssp. occidentalis in Douglas et al. 1999).

Phlox speciosa can be distinguished from other Phlox species in British Columbia by its erect stature, opposite leaves (1-7 cm long), stalked flowers, glandular calyces, and short styles 0.5-2 mm long. The most similar species is Phlox longifolia, but it has very distinctive long styles (6-15 mm long).

Additional descriptions and keys for Phlox speciosa[ssp. occidentalis] are available in American floras (see Hitchcock et al. 1959; Peck 1961; Cronquist et al. 1984; Hickman 1993).

Figure 1.  Photograph of Phlox speciosa taken in British Columbiain 2003. The flower colour is darker pink than is typical for British Columbia populations.