Alleghanian—Ozark Distriet: Ozark Plateau. 515 
and lower Cross Timbers are of this type. — The open forests of the granite 
region of the Carboniferous area and of the isolated gravel terraces as those 
above the Colorado River at Austin, where on the picturesque banks of 
this river grows Carya olivaeformis (Hicoria Pecan), Populus monilifera, Plata- 
nus, Quercus virginiana (Q. virens), O. rubra, O. nigra, O. macrocarpa, O. 
Palustris, Sapindus Drummondii and Funiperus virginiana. Beyond the Neuces 
River, the post oak formation loses its identity. Ouercus marylandica and 
obtustloba constitute the chief elements in this type of forest, the post oak 
(O. odtusiloba) forming the more abundant and larger growth. 
2. Rock Cliff Formations. 
On wet and dripping rocks, the vegetation forms an association of species 
that may be designated the Fontinal Association. Here occur the walking 
fern Camptosorus rhizophyllus, liverworts Conocephalus conicus, Grimaldia 
rupestris and Dumortiera hirsuta. A few phanerogams are found. These 
plants occupy the lowest portions of such dripping rocks. Above them grows 
an association of ferns Cystopteris bulbifera, C. fragilis, Woodsia obtusa, As- 
Plenium platyneuron, Nephrodium acrostichoides and such flowering plants as 
Arabis laevigata, A. dentata, A. canadensis and Erigeron Philadelphicus. The 
next association of plants occupies the upper portion of wet clifis, or often 
whole sides of low moist cliffs. The crevices and cracks of the rocks ac- 
comodate Aguslegia canadensis and Solidago Drummondii while the ferns 
Woodsia, Cystopteris fragilis, Pellaca atropurpurea, P. dealbata (very rare), 
Chetlanthes lanuginosa ogcupy such situations, The summit edge of the cliff 
usually very dry and sterile is characterized by Androsace occidentalis, Draba 
cuneifolia, Scutellaria campestris and parvula, Astragalus distortus, Carex 
setifolia, Arenaria texana, Allionia hirsuta Ar 
The forest of the cliff summits that occupies the verge of the clifis along the Missouri is 
dominated by Quercus acuminata, Q. minor (= Q. obtusiloba), Q. marylandica, Acer saccharum, 
Fraxinus quadrangulata, Carya alba (= Hicoria ovata), C. amara (= Hicoria minima), Diospyros 
virginiana, Juniperus virginiana, Amelanchier canadensis, Celtis occidentalis, Ostrya virginiana, 
Cornus asperifolia, C. Drummondii, Viburnum rufotomentosum, Morus rubra, Vaccinium vacillans 
(south of Grindstone Creek), Mentzelia oligosperma (along clifis of the Missouri River). e 
characteristic herbs are Solidago Drummondii, S, radula, S, speciosa, Aster anomalus, A. turbinellus 
and A. oblongifolius. 
The clifis along the Mississippi River, according to Hus, are almost perpendicular and 
sometimes even concave with soil in the numerous crevices of the rock faces. The plants of the 
spring flora which chiefly occur as rosette-forming annuals are Arabis canadensis, Draba 
cuneifolia, Erysimum erum, Lechea major, Silene antirrhina, As us mexicanus, Polygala 
verticillata, Heuchera hispida, Androsace oceidentalis, Phlox pilosa, Lithospermum canescens, 
Monarda Bradburiana, Scutellaria parvula, and such grasses as Melica diffusa, Panicum depaupe- 
ratum. At this time Eryngium yuccaefolium, Agave virginica, Verbascum thapsus enlarge their 
en 
ir} 
1) Consult WARMING, Eug.: Oecology of Plants 1909: 239-247 for details as to the 
adaptations of rock plants, etc., and compare HARSHBERGFR, J. W.: The plant Formations of the 
Nockamixon Rocks, Penna, Bulletin Torrey Botanical Club XXXVI: 651—673. 
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