BOTN 201 - Department of Biology - TAMU
Images of the Navasota Flora - 2 April 1995

A large population of 'Yellow-Flag' Iris inhabits the margin of Lake Placid (Bird Pond Road, just West of Carter Creek). This species, Iris pseudacorus, not a Native Texan, was originally brought to the area as a cultigen and eventually 'escaped' to join cogeners in the wild flora. A native species, Iris virginica shows blue perianth parts. A close look reveals one of the three stamens (a good key character for the Iridaceae within the context of the Liliidae) that lies between the petaloid style branch and subtending tepal (note yellow pollen vector guide of the tepal). While Iris virginica is a native species, this particular plant is growing under cultivation in a garden at Foxfire. It shares this habitat with the common domesticated Iris of the Navasota Valley, Iris pallida. The flower of Iris pallida, with the subtending bracts removed, shows epigyny, another family characteristic. A close look also reveals that the tepal subtending the stamen is 'bearded', a mark of Eurasian elements of the genus. While this species does not 'escape' from cultivation and become established in the local flora, it will remain in gardens and thereby sometimes stand as the only mark of past human occupation. This plant was taken from from an old homestead site positioned near the old-growth Post Oaks (Quercus stellata) that stand near the parking lot at Lick Creek Park.

More important, from an ecological point of view and certainly less attractive from the perspective of both pollen vectors and gardeners, is our most common species of the large genus Carex (Commelinidae - Cyperales), C. cherokeensis. It is the dominant herbaceous element of the local 'sedge meadow' vegetation type this is best preserved locally in the wooded bottomlands of Lick Creek Park. This Carex species, now in full fruit, is monecious with flowers arranged in staminate and pistillate inflorescences. This is also the case with Carex flaccosperma, as indicated by inflorescences at anthesis. As the pistillate inflorescences mature, the distinctive perigynia (a green 'bag' that encloses the ovary) of this genus are evident. Another species, C. bushii shows staminate flowers and pistillate flowers on a single inflorescence, with the staminate flowers subtending the terminal pistillate flowers. A close look reveals the large, plump perigynia characteristic of this species. This contrasts with those produced by C. cephalophora. This species is marked by reduction of bracts subtending the inflorescences, mixture of staminate and pistillate flowers, and relatively compressed or flattened perigynia. All three Carex species show the triangular, pithy culm (stem) that marks many genera of the Cyperaceae or 'Sedge' family as opposed to related genera of the Poaceae (Gramineae) which usually show terete (round) culms.


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Last updated by HDW on 4 April 1995