Cubelium concolor (T.F. Forst.) Raf. ex Britton & A. Br.

Green Violet

Cubelium concolor plant

SRTurner

Family - Violaceae

Habit - Perennial forb with rhizomes and dense fibrous roots.

Stem - Strongly ascending to erect, to 1 m, with 8 to numerous nodes, usually unbranched, usually pubescent with spreading hairs, occasionally glabrous.

Cubelium_concolor_stem.jpg

Stem and node.
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Leaves - Alternate, or the lowermost sometimes opposite, short petiolate to nearly sessile, the petiole narrowly winged. Stipules relatively inconspicuous, 4-15 mm long, linear to narrowly lanceolate, the margins entire. Leaf blades 4-12 cm long, unlobed, oblanceolate, tapered to a usually sharply pointed tip, angled at the base, the margins entire or with a few, small, irregularly spaced teeth toward the tip, the surfaces glabrous or sparsely to moderately hairy, sometimes only along the veins of the undersurface.

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Leaf adaxial.
SRTurner

Cubelium_concolor_leaf2.jpg

Leaf abaxial.
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Inflorescences - Solitary axillary flowers or some of the nodes with small clusters of 2 or 3 flowers, the stalks short, drooping at flowering (usually becoming longer, straighter and spreading at fruiting), bractless, but jointed near the midpoint.

Flowers - Cleistogamous flowers rarely observed in Missouri plants. Chasmogamous flowers with sepals 1-3 mm long, narrowly lanceolate to nearly linear, S-shaped or inward-curved, sharply pointed at the tip, the margins entire but sometimes hairy, lacking auricles. Corollas 2-3 mm long, uniformly greenish white, the petals oriented forward or spreading in life, the lowermost petal often slightly pouched but not spurred. Stamens with the filaments free or partially fused, the dorsal surface of the 2 lowermost often bearing a small gland, the anther appendages oblong to ovate, entire, membranous, orange to white. Style slender, somewhat S-shaped, slightly thickened at the tip, the stigma directed downward, slender, lobed or tapered.

Cubelium_concolor_flowers1.jpg

Flowers.
SRTurner

Cubelium_concolor_flowers2.jpg

SRTurner

Fruit - Capsules 17-26 mm long, oblong-ellipsoid, green when fresh, drying to tan, glabrous, dehiscing explosively. Seeds 1 to several per valve, 3-4 mm long, mostly subglobose, the surface smooth, white to cream-colored, lacking an aril or rarely with a small aril.

Cubelium_concolor_fruit1.jpg

Fruit.
SRTurner

Cubelium_concolor_fruit2.jpg

Dehiscent fruit.

This view is not often seen, as the capsules commonly dehisce violently, forcibly ejecting the seeds.
SRTurner

Flowering - April - June.

Habitat - Forests, bluffs, glade margins, often on calcareous substrate.

Origin - Native to the U.S.

Lookalikes - None.

Other info. - Although it's in the violet family, this little plant looks nothing at all like other Missouri violets. Even when in full bloom, as in the top photo, it is easily overlooked. This is a common species in Missouri, less so in the northern and western parts of the state. Its main distribution extends in a broad band eastward from Missouri and Arkansas, and also into Canada.

A synonym for this species is Hybanthus concolor. The species has been divided by some authors into infraspecific forms. One of these is f. subglabrum Eames, which has glabrous stems. The hairy form is by far the more common in Missouri. In favorable locations the plant can be quite abundant.

Photographs taken at Washington State Park, Washington County, MO, 5-4-2014, Valley View Glade Natural Area, Jefferson County, MO, 5-24-2014, and Glassberg Conservation Area, Jefferson County, MO, 9-25-2014 (SRTurner).



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