White meconella (Meconella oregana) COSEWIC assessment and status report: chapter 3

Species Information

Name and classification

Meconella oregana Nutt. is a member of the Papaveraceae and is one of only three species in this genus.  In Canada it is the only Meconella species and has no recognized subspecies or varieties.

Varieties and subspecies of Meconella oregana described in the past have been subsequently renamed (Kartesz pers. comm. 2004). Meconella californica Torr. & Frém. was formerly known as Meconella oregana subsp. californica (Torr.) E. Murray, Meconella oregana var. californica (Torr. & Fremont) Jeps., Meconella oregana var. californica Jepson, Meconella oregana var. octandra (Greene) Jeps. and Meconella oregana var. octandra Jeps. Meconella denticulata Greene was formerly known as Meconella oregana var. denticulata (Greene) Jeps. and Meconella denticulata Jeps. (ITIS 2002; Kartesz pers. comm. 2004). 

Former generic synonyms for this species included Platystigma oreganum Brew. & Wats. (1876) and Platystemon oreganus Curran (1887) (Hitchcock and Cronquist 1964). The current taxonomic status of this species is accepted (ITIS 2004). Genetic analysis of the family supports the current classification (Hoot et al. 1997).

English names for Meconella oregana include Oregon meconella, white fairypoppy, white meconella and Oregon poppy (Douglas et al. 1999; Rush et al. 1999; California Native Plant Society 2003; NatureServe 2003; Sacramento Fish and Wildlife Office 2003; ITIS 2004; Washington Natural Heritage Program 2004).

In California where this species’ range overlaps with Meconella californica and Meconella denticulata, there has been confusion over the identification of specimens in Contra Costa and Santa Clara counties. As a result, Meconella oregana was not included in the new Jepson Manual, but has since been recognized to occur in California (Flora of North America Editorial Committee 1993; California Native Plant Society 2003; Clark pers. comm. 2004).[1]

Morphological description

Meconella oregana is a small annual herb from a slender taproot. The stems are erect to ascending and are either solitary or sparingly branched from near the base. When in bloom the plants range from 2 to 16 cm tall and are smooth and blue-green in colour (Flora of North America Editorial Committee [eds.] 1993+; Douglas et al. 1999). British Columbian specimens range from 1 to 8 cm (writer’s observations).

The species has spoon-shaped, entire leaves that form a basal rosette. The basal leaves are 3-18 mm long including the 1-10 mm petiole. The 5-9 mm stem leaves are opposite, lanceolate to linear in shape and unstalked (Douglas et al. 1999; Rush et al. 1999; Washington Natural Heritage Program, 2004).

The solitary flowers are borne on hair-like axillary or terminal stalks that are often longer than the stem. Flowers usually have 6 egg-shaped white petals (1.3-4 mm long) and 3 sepals (Flora of North America Editorial Committee [eds.] 1993+; Douglas et al. 1999).  Stamens number 4-6 and are in one series (Flora of North America Editorial Committee [eds.] 1993+). The flowers may also have irregularities including fused petals or stamens, missing petals or stamens and/or irregular symmetry (Ernst 1967). 

Meconella oregana produces many seeded, green and later tan to brown linear capsules. The capsule size is 1-1.6 cm long x 0.1 cm in diameter (Gunn and Seldin 1976; Gunn 1980). The capsules do not form valves but release the seed by splitting through the placentae (Ernst 1962). The seeds are smooth and shiny and range in colour from amber to blackish. Seed size is 0.6-0.8 x 0.4-0.6 x 0.3-0.4 mm (Gunn and Seldin 1976; Gunn 1980). Figure 1 illustrates the general appearance of the species.

Genetic description

Meconella oregana is diploid and has a chromosome number of n=8. The chromosomes are smaller than those of other species in the subfamily Platystemonoideae (Ernst 1967).

Figure 1. A small patch of Meconella oregana, some fruiting. The plants are ca. 4 cm tall.

Figure 1.  A small patch of Meconella oregana, some fruiting. The plants are ca. 4 cm tall.

[1] In California Meconella oregana specimens may be confused with depauperate Meconella californica except that M. californica generally has larger petals (8-10 mm rather than 2.5-4 mm), has a larger number of stamens (6-16 rather than 4-6), and the stamens are in two series rather than one (Munz and Keck 1959; Ernst 1967; Flora of North America Editorial Committee [eds.] 1993+).  Long cylindrical anthers distinguish Meconella denticulata from Meconella oregana, which has globular anthers (Hannan, pers. comm. 2004).  Meconella oregana can be distinguished from Platystigma linearis Benth. by the presence of both basal and stem leaves and white rather than yellow flowers (Munz and Keck 1959; Rush et al. 1999; Washington Natural Heritage Program 1992; Washington Natural Heritage Program2004). Meconella oregana may also be confused with annual mustards, although the plants are very distinctive when in flower (Washington Natural Heritage Program 1992).

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