E-Flora BC: Electronic Atlas of the Flora of British Columbia

Marah oregana (Torr. ex S. Watson) Howell
Cucurbitaceae (Cucumber family)

Introduction to Vascular Plants

© Jamie Fenneman  Email the photographer   (Photo ID #9434)

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Distribution of Marah oregana
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Manroot is a long-lived vine in the Cucumber Family (Cucurbitaceae) that is found in North America "from southern British Columbia to central California, mostly west of the Cascade Mountains." (COSEWIC 2009). In Canada, it is found at the northern edge of its range, and "it only occurs in a small area extending from southeast Vancouver Island to Pender Island in the Southern Gulf Islands" (COSEWIC 2009). It is found at low elevations, often within 30m of the water's edge, and distribution is correlated with Garry Oak (Quercus garryana) (COSEWIC 2009).

Manroot has distinctive 'cucumber'-type leaves (irregularly palmately lobed), annual trailing stems, inflated spiny fruits with enlarged seeds, and large tubers.

This is a red-listed species in BC that is considered endangered in Canada by COSEWIC: "fewer than 20 mature plants remain with no evidence of seedling production" (COSEWIC 2009). It is threatened by habitat loss, invasive species, trampling, and "chance events affecting the handful of remaining individuals" (COSEWIC 2009).

"Plants in this group are noted for their large perennial underground tubers, which can weigh in excess of 100 kg...." (COSEWIC 2009).

Specific details on habitat, reproduction and germination, herbivory, physiology and climatic requirements are provided in the COSEWIC status report.

Species Information

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Climbing perennial from an enlarged woody root; annual stems climbing or trailing with branched tendrils.
Stem leaves alternate, irregularly palmately lobed, stalked, bristly above, sparsely hairy below, heart-shaped at the base, about 20 cm long.
Inflorescence of bell-shaped flowers in a panicle; perianths bell-shaped, whitish, with 5 to 8 petals/sepals; male flowers in narrow-stalked clusters from the leaf axils; single female flowers short-stalked from the same axils as the male flowers; corolla lobes flaring, oblong egg-shaped.
Inflated, weakly spiny bladders, ellipsoid to oblong egg-shaped; seeds 1 or 2 in each locule, turgid, smooth.

Source: The Illustrated Flora of British Columbia

Habitat / Range

Moist fields and open meadows and slopes in the lowland zone; rare in SW BC, known only from Vancouver Island and the Gulf Islands; S to N CA.

Source: The Illustrated Flora of British Columbia

Synonyms and Alternate Names

Marah oreganus (Torr. ex S. Watson) Howell

Taxonomic and Nomenclatural Links

Additional Photo Sources

General References