Anna Saghatelyan - Botanical Research Institute of Texas

410 Journal of the Botanical Research Institute of Texas 3(1)
canadensis). Western American (Cordilleran) genera have six species (Muhlenbergia rigida, Epilobiium
ciliatum), while 5 species of Amaranthus and Heliotropium are mostly Caribbean.
4a. american trop/Subtr: widely distributed in tropical and subtropical (warm temperate) parts of
the Americas. This sub-element has 30 of the 101 sp. of the American element with the grasses
(Cenchrus myosuroides) being especially numerous. Other examples are Tillandsia recurvata, Solanum
elaeagnifolium, Phyla nodiflora, and Ipomoea cardiophylla.
5. North american: more or less wide ranges in temperate regions of North America; 98 mesophytic species.
They either belong to widely north temperate genera (Maianthemum racemosum, Carex hystericina, and
Vicia americana), north American genera (Solidago gigantea, Lobelia cardinalis, Monarda fistulosa), or cosmopolitan
genera with large sections in temperate latitudes (Euphorbia cyatophora). Herbaceous habit,
especially in the grasses (18 sp.), sedges (8 sp.), Asteraceae, and Euphorbiaceae (6 sp. each) predominate.
A few older montane woody species have interesting ranges: either absent in the south-eastern and
south-central region (Prunus virginiana), poorly represented in the western and absent in the central
(Cephalanthus occidentalis) region, or those that tend to the Rocky Mountain (Cheilanthes feei) Region.
6. East North american: wide ranges in the Atlantic North American Region of Cronquist (1982). Representatives
of ancient Laurasian genera are essential among the 37 sp. of this geoelement (Ostrya virginiana,
Carya ilinoensis, and Clematis pitcheri). A few species however have tropical connections (Cocculus
carolinus, Celastrus scandex, and Nothoscordum bivalve).
6a. Gulf Coast-(Caribbean): with ranges in the namesake provinces (Thelipteris ovata, Melothria pendula).
6b. appalachian: with ranges in the namesake province (Ostrya virginiana, Melica nitens).
7. Comanchian/ SC US: Edwards Plateau westward to the Trans-Pecos extending northward into central
Oklahoma or further to Ozark Plateau, southward into northeastern Mexico and western Lousiana,
mainly in the limits of the Comanchian Subprovince of McLaughlin (2007). There are 46 species in
this geoelement like Juniperus ashei, Lupinus texensis, and Scutellaria wrightii, with some having disjunct
relictual ranges (Leptopus phyllanthoides).
8. Prairie: wide ranges in the North American Prairies Province of Cronquist (1982); 85 mostly herbaceous
species. Biggest group of 24 sp. is in Asteraceae (Liatris punctata, Hymenopappus scabiosaceous), especially
in the Heliantheae s.l. (Panero & Funk 2002). Poaceae (Bouteloua dactyloides, Schedonnardus paniculatus),
and papilionaceous Fabaceae (Astragalus lotiflorus, Dalea aurea) have 7 sp. each. Remaining species
are in large temperate genera (Oenothera triloba, Salvia azurea) with big centers of diversity in western
America and Mexico.
8a. S Prairie/SC North american: from Central and South Texas extending northward to adjacent
states and southward to northern Mexican Plateau (Eryngium leavenworthii, Argythamnia humilis,
Rhus lanceolata, and Gaillardia suavis).
9. W North american: wide ranges in the entire western North America or its parts mostly north of Mexico.
Among the 133 sp. of this geoelement 28 sp. of Asteraceae (Brickelia californica, Erigeron divergens)
prevail, followed by 18 sp. of Poaceae (Agrostis exarata) and 9 sp. of Brassicaceae (Stanleya pinnata).
Western American genera have numerous species (Glossopetalon spinescens, Cryptantha cinerea) including
the dominants in different types of communities. Examples range from those of montane forests (Pinus
ponderosa, Quercus gambelii, and Cercocarpus montanus), Rocky Mountain and Madrean woodlands and
shrublands (Juniperus scopulorum, Rhus trilobata, Holodiscus dumosus), to widely distributed xerophytic
(Opuntia polyacantha) as well as riparian (Salix exigua) species.
9a. WC US/ WC North american: includes western mountainous (not Pacific) region and western
half of the Prairies Province in the United States/or southward to central Mexico; this element
supports S. McLaughlin’s (2007) Western Region. Of the 133 sp. of W North American element,
29 sp. are in this sub-element. They belong to large temperate genera (Astragalus, Cirsium, and
Lithospermum), North American genera (Monarda pectinata, Oenothera albicaulis), or a few tropical
(Heliotropium convolvulaceum) genera.