Prairie- and Sand Hill District. 535 
2. Mat Rosette Formations of Buttes, Cliffs and Hills. 
This is the chief of the foot-hill formations in Nebraska. Almost the sole 
vegetation is sparse and of the mat or rosette type on buttes, cliffs on rocky 
hills, rocky ridges and on sandy hillsides. At times a considerable number of 
secondary species occupying the intervals between the mat-forming species. 
‘The monotony found in the bunch-grass formations is relieved in this formation 
by the bright and showy flowers. Two types may be distinguished (a) the 
mat formation of buttes and cliffs, including also the mat formation of rocky 
ridges and stony hills and (b) the rosette formation of sandy hillsides. 
Mat Formation of Buttes and Cliffs. This varies considerably in respect 
to the constituent species. 
Thus on Scott’s is according to POUND and CLEMENTS are found Arenaria Hookeri, 
Gilia spicata, Phacelia circinata (= P. heterophylla), Astragalus c. er Eriocarpum grindelioides 
(= Aplopappus Nuttallii), VE (Stenotus) armerioides, Picradenia acaulis, Eriogonum cer- 
nuum, Town Rer= sericea (= T. exscapa) while Arenaria ie Gilia p pungens var. caespitosa, 
G. iberidifolia, Phlox Hoodii, Feriogoiik flavum, E. multiceps, E. cernuum, Musineon tenuifolium. 
Astragalus (Orop ia sericeus, Homolobus caespitosus and Hi EEE (= engl Kiss 
are characteristic on the cliffs and foothills of the Lodge Pole territory of Nebrask e chalk 
rocks of this territory support Gilia iberidifolia, G. congesta and Phlox Hoodii = Oreocarya 
fulvocanescens is a cliff inhabitant. The buttes of the Hat Creek basin show Eriogonum flavum, 
Sedum stenopetalum, and Eriocarpum grindelioides (= Aplopappus Nuttallii), Berberis sr 
(= B. aquifolium) and Symphoricarpos pauciflorus are to be met with on the buttes or uppe 
canyon sides in this basin. The secondary species are emigrants from other xerophytie josae 
In the Lodge Pole territory the dominant and characteristie plants of rocky ridges and 
high, stony hillsides are Phlox bryoides, P. Hoodii, Arenaria Hookeri, Eriogonum flavum, Les- 
querella we Townsendia exscapa and Viola Nuttallii. Cheilanthes lanuginosa grows on the 
exposed rocks. — Forming dense cespitose masses on hi igh rocky situations in the Pine Ridge 
country are Hokalcber caespitosus, Gilia pumila, Arenaria Brere Eriogonum flavum, Loeflingi 
texana and here and there are Euphorbia montana, Opuntia humifusa, O, missouriensis (= O 
polyacantha) and Thermopsis rhombifolia. Cercocarpus ee is an undershrub of ii 
situations. 5 
Rosette Formation of Sandy Hillsides. The hills over which it prevails are 
not unlike the true sandhills being almost pure sand and very sparsely covered 
with vegetation, but they have no blow-outs and the bunch-grasses are absent. 
Rosette plants are prominent. 
Hill after hill will >> covered sparingly with Polygala alba, Pentstemon albidus, P. eaeruleus 
(= P. angustifolius), P 0x Douglasi, Paronychia Jamesii, Astragalus sericeus and Oreocarya suf- 
fruticosa (= Krynitzkia nn Polygala alba and Paronychia Jamesii are the most important and 
5. Pe tion e 
Stipa comata with Rumex venosus, Astragalus sericeus is almost buried in the sand. EIs ewhere 
Gilia spicata, Oenothera re Arenaria Hookeri, Paronychia Jamesii, Pentstemon er: take 
rt in the rosette format 
Sandstone Bluff Formation. This formation of several associations is found 
along the bluffs which border the deep narrow valleys of the streams in the 
