Wayne Armstrong's On-line Description of Wolffiella oblonga (Lemnaceae)
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Wolffiella oblonga

(R.A. Philippi) C. Hegelmaier

Oblong Mudmidget

Bot. Jahrb. 21: 303; 1895


Roots: None

Shape of Plant Body: Flattened, narrow-oblong to linear, straight or slightly falcate, with free end (apex) not or only slightly curved downward into water.

Size: 1-2 mm wide and 3-4 (5) mm long ( generally 3-5 times as long as wide).

Veins: None in plant body; faint tract of elongated cells (costa) visible in budding pouch.

Budding Pouch Position: One flattened, triangular pouch at basal end; budding pouch angle 40-70 degrees; costa situated along edge of lower wall of pouch; aerenchyma tissue (region of air spaces at basal end) generally extending longer than wide.

Flower (Fruit) Position: Within floral cavity near basal end of dorsal surface, not enclosed by spathe; in flowering plants the basal end floats just at the water surface so that stamen and pistil are held above water.

Arrangement of Clonal Clusters: Solitary or 2-several connected; sometimes connected in star-shaped clusters of up to 8; daughter plant sometimes oriented at angle to right or left of parent plant, giving combined plants a boomerang appearance when viewed from above.

Habitat: Floating at surface or submersed in fresh water ponds, marshes and quiet creeks, often beneath other Lemnaceae and aquatic plants.

Range: Scattered distribution in ponds and marshes at low elevations in coastal and interior valleys of central and northern California; unknown north of California; widespread in temperate and tropical regions of the western hemisphere, including the southeastern United States, Mexico, Central and South America.

Other Information:

This sp. distinguished from optimal vegetative growth forms of its congener W. lingulata (Hegelm.) Hegelm. by its smaller, narrower plant body which is generally flat and not conspicuously recurved; the more acute budding pouch angle and position of costa on lower wall of budding pouch are probably the best means of separating this sp. from small, impoverished growth forms of W. lingulata; this sp. possibly could survive in some of the mild valleys of coastal and interior Oregon; reported from coastal and interior valleys of southern California, but these populations are probably extirpated due to urbanization, flood control channelization and pollution.

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