Lowland Rotala, Tooth Cup: Rotala ramosior (Synonyms: Rotala catholica, Rotala dentifera, Rotala ramosior var. interior, Rotala ramosior var. typica)

Tooth cup as seen along the Columbia River shoreline north of Richland, Washington..............October 3, 2012. Note the opposite leaves which taper to a petiole and the bell-shaped, shallowly 4-lobed hypanthium in each leaf axil. This species typically has 1 (typical) to 3 flowers at each leaf axil. The hypanthium typically measure 1.5-2.5 mm long in flower and 3-4 mm wide in fruit (See photos further below.)

Tooth cup as seen along the shoreline of the Columbia River north of Richland, Washington...............October 3, 2012. Plants in the habitat view were found near the top of the green vegetation zone pictured, at a place where the soil transitioned from moist mud to more of a sandy structure.

Additional close-ups of tooth cup as seen along the Columbia River shoreline north of Richland, Washington............September 2, 2012. Note the single, axillary hypanthiums which become globose as they mature. Note also the very short styles in the lowest photos. Some of the leaves shown here suggest those of the similar Ammania robusta which has sessile to clasping leaves, but it typically has axillary flowers in clusters of 1-5 with a longer style slightly exserted from the mouth of the pale lavender flowers. It would be good to see these with fresh flowers for comparison and positive ID. Note the seeds nearing release from several of the capsules in several photos.