Excerpts from Jim Conrad's
Naturalist Newsletter

Gentian-leaved Spiderwort, TRADESCANTIA ZANONIA, in habitat

notes from the May 10, 2015 Newsletter describing a camping trip, in the last week of April, in the hydrological reserve above San AndrésTuxtla, Veracruz, México

During our travels we've met with several spiderwort species, members of the genus Tradescantia. Spiderworts belong to the Spiderwort Family, the Commelinaceae, a monocot family on the Phylogenetic Tree of Life found not far from the Lily Family. Spiderworts are herbs with somewhat succulent leaves and parallel veins. Their flowers bear three conspicuous petals colored with hues in the blue to red-purple part of the spectrum, and six stamens.

On my camping trip during the last week in April in the mountain-top hydrological reserve above and to the north of San Andrés Tuxtla, Veracruz, Mexico, I met with an interesting spiderwort I'd never seen. It turned up along a deeply shaded trail through the cloud forest, groping toward a sunbeam entering through a break in the canopy above the trail, as shown at the top of this page in a flash-assisted picture.

This spiderwort species was much "leggier" than most -- lots of stem for the number of leaves. Also, as shown below in very dim light, the flowers were smaller than usual, with curious, upside-down-V-shaped anthers attached at their middles:

Gentian-leaved Spiderwort, TRADESCANTIA ZANONIA, flowers

Remarkably, the plant's capsular fruits were wholly enveloped by fleshy, purplish-black calyxes, as shown below:

Gentian-leaved Spiderwort, TRADESCANTIA ZANONIA, black, calyx-enveloped fruits

Where leaves attached to the stems, a fringed, collar-like affair surrounded the stem, shown below:

Gentian-leaved Spiderwort, TRADESCANTIA ZANONIA, node

With such unusual traits, this spiderwort quickly revealed itself as TRADESCANTIA ZANONIA, sometimes known as Gentian-leaved Spiderwort. The species occurs in moist to wet forests from southern Mexico south to Bolivia and Brazil, as well as the Caribbean area.

Not much is known about the species. It's thought that its capsular fruits may never split open to lose their seeds the normal way but that, rather, birds are attracted by the black, shiny calyxes covering the fruits, and eat the fruit and calyx together, later to disseminate the seeds the usual way.

A cultivar sold under the trade name Mexican Flag and listed as Tradescantia zanonia is strongly variegated with white and green stripes, and close-together leaves, looking very unlike like this wild Tradescantia zanonia. You can see pictures of the cultivar at http://davesgarden.com/guides/pf/go/102116/.