Wild Flowers of Pittsburgh

Commelinaceae

Spiderwort (Tradescantia virginiana)

A native plant that is perhaps even more common in gardens than in the wild; the purple to blue flowers with three equal petals and the linear, almost grasslike leaves are distinctive. The closest common relatives in our area, the Dayflowers, have three unequal petals and much shorter leaves. Like Dayflowers, these bloom in the morning and disappear by the middle of the afternoon. This plant was part of a colony growing beside a railroad in Oakmont, where it was blooming in late May.

Gray describes the genus and the species:

TRADESCÁNTIA [Rupp.] L. SPIDERWORT. Flowers regular. Sepals herbaceous. Petals all alike, ovate, sessile. Stamens all fertile; filaments bearded. Capsule 2-4-celled, the cells 1-2-seeded — Perennials. Stems mucilaginous, mostly upright, nearly simple, leafy. Leaves keeled. Flowers ephemeral, in umbeled clusters, axillary and terminal, produced through the summer; floral leaves nearly like the others. (Named for the elder Tradescant, gardener to Charles the First of England.)

T. virginiàna L. Green; leaves flat, linear or lance-linear, the upper moге or less pubescent; bracts loaf-like, elongated, usually ascending; pedicels and sepals villous, the latter about 1.6 cm. long; petals rich purplish-blue, 1.6-2 cm. long — Alluvial soil, Ct. to Pa. and S. C.: also introd. northw.


Dayflower (Commelina communis)

Commelina-communis-2009-08-30-Beechview-02

Also called “Wandering Jew,” and a close relative of the Wandering Jew often found in supermarket hanging baskets. This is the Asiatic Dayflower: the two upper petals are pure blue; the lower one is white. Virginia Dayflower, a native but rarer species, has a blue lower petal. The flowers close in the late afternoon; thus the name. We find this common flower everywhere, blooming all summer till frost; here it was blooming beside a front porch in Beechview.

Gray describes the genus and the species:

COMMELINA [Plum.] L. DAY-FLOWER
Flowers irregular. Sepals somewhat colored, unequal; the 2 lateral partly united. Two lateral petals rounded or kidney-shaped, on long claws, the odd one smaller. Stamens unequal, 3 of them fertile, one of which is bent inward; 3 of them sterile and smaller, with imperfect cross-shaped anthers; filaments naked. Often procumbent and rooting at the joints. Leaves contracted at base into sheathing petioles; the floral one heart-shaped and clasping, folded together or hooded, forming a spathe inclosing the flowers, which expand for a single morning and are recurved on their pedicel before and afterward. Petals blue. Flowering all summer. Ours all with perennial roots, or propagating by striking root from the joints. (Dedicated to the early Dutch botanists J. and G. Commelin.)

C. communis L. Slender and creeping, nearly glabrous; leaves lanceolate, 2-5 cm. long; spathe cordate, acute, with margins not united; seeds shallowly pitted, granulate-reticulated. (C. nudiflora auth., not L.) Alluvial banks, Del. to Fla., w. to Kan. and Tex. A frequent weed of dooryards and gardens, northeastw. to e. Mass. (E. Asia, Trop. reg.)


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