BOTN 201 - Department of Biology - TAMU
Images of the Navasota Flora - 12 March 1995

Here is the status of several monocot (Class Liliopsida) species of the Navasota Flora as of the 12th of March, 1995.

Of several local 'Spiderwort' or Tradescantia species (Commelinaceae), T. subacaulis is the first to flower.

It shows typical floral structure of the Commelinaceae (monocot subclass Commelinidae in that the perianth is showy but, as opposed to most taxa of the related subclass Liliidae, the calyx and corolla are clearly distinct. Staminal hairs, unusual multicellular strands connected to the androecium (floral ZOOM) are present in T. subacaulis and a relative from the ethnoflora. This plant, perhaps T. albiflora of South America, shows its connection to the native Texas species by close inspection of its small, white flowers.

Other monocots (Class Liliopsida) coming into flower this week include two 'grasslike' plants that are NOT grasses (Poaceae/Gramineae). The Wood Rush, Luzula bulbosa of the Juncaceae inhabits openings of the local Post Oak woodlands. The plant shows the linear leaves and tight clusters of small flowers of the Poaceae, but a close look reveals a key character of the Rush Family (Juncaceae) that separates it from true grasses and sedges (Cyperaceae), i.e., the presence of a perianth.

A common inhabitant of aquatic margins (ditches, lake/stream margins) is the Spike Rush:

This is one of several Eleocharis species (Cyperaceae) represented in the Navasota Flora. Its caespitose habit (clustered stems) and small, clustered inflorescences mark the 'grass-like" syndrome. However, close inspection of the Eleocharis inflorescence reveals that each terminal 'spikelet' (inflorescence) is subtended by only a single bract, as opposed to the glumes of the Poaceae, and each flower is also subtended by a solitary bract, as opposed to the 'fertille bracts' (palea/lemma) of the Grass Family. In contrast to many genera of the Sedge Family, Eleocharis species are perfect flowered. To maximize outcrossing, this species shows sequential development of the inflorescence in that stigmas emerge after full androecium development and anther dehisence. This is evident by close inspection of Eleocharis inflorescences taken from a series of plants.

As the name Eryngium yuccifolium implies, this species has the vegetative look of a typical monocot (the genus Yucca of the Agavaceae):

This, however, points out an exception to the genera rule in that the genus Eryngium is an atypical genus of the Carrot Family (Apiaceae/Umbelliferae) and E. yuccifolium is an atypical species of the genus with its 'yucciform' foliage. This is an herbaceous perennial that often marks relatively undisturbed, mesic prairie habitats in the Navasota Valley.

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Last updated by HDW on 13 March 1995