432 



Illinois Natural History Survey Bulletin 



Vol. 2b, Art. 5 



Xanthoxyhim americanuin Mill. Prick- 

 ly ash was seen in Balk prairie, where it 

 was growing; in loess. The woodlands ad- 

 joining many other prairies contained this 

 species ; only at Balk had it strayed into the 

 prairie. 



POLYGALACEAE 



Polyyala incarnata L. This milkwort 

 was found in loess on the crest of the 

 ridge at Northeast Meredosia. 



Polygala verticillata L. This species, 

 easily overlooked in its location between 

 tufts of grass, was observed in nine prai- 

 ries from Fountain Bluff northward. 



KUPHORBIACKAI; 



.Ictilyftlia ijracilens Gray. Tiiis three- 

 seeded mercury grew on the rocky prairie 

 slopes and sandstone ledges at Fountain 

 Bluff. 



ChatiKUsyif ylyplnspfrma (Fngclm.) 

 Small. {Kiiplwrhia ijlyptuspcrma Fn- 

 gelm.] 'iliis plant was found in rock 

 prairie at Devil's Backbone. 



(jhamavsyce maculata (L. ) Small. 

 [Euphorbia inatiilata L.] Nodding spurge 

 was seen in 14 hill prairies; in none of 

 them was it abundant. 



Chamaesyce supina ( Raf . ) Moldenke. 

 [Euphorbia supina Raf . | Milk-purslane 

 was found between the bunches of grass 

 in six hill prairies. It was observed also 

 in crevices of ledges. 



Croton capitatus Michx. Hogwort was 

 found only at Principia and Fdgcmont. 



Croton (ilandulosus var. septentrionalis 

 Muell. Arg. Sand croton was found only 

 at Bluff Springs and Block House. 



Croton monanthogynus Michx. Prai- 

 rie-tea, a frequently encountered plant in 

 hill prairie, was observed at 19 sites in 

 central and southern Illinois. 



Euphorbia corollaia L. Flowering 

 spurge, a common plant in prairies, glades, 

 and rocky ground, was found in 36 hill 

 prairies, where it grew in loess and rocky 

 soil. It was found also in some adjacent 

 woodlands. 



*Euphorhia cyparissias L. Cypress- 

 spurge, or cemetery cypress, was found 

 in the Seehorn-Payson prairie as an escape 

 from a nearby cemeter\ . 



Euphorbia obtusata Pursh. 'Ibis spe- 

 cies was collected at Fults. 



Poinsfltifi dcntata (Michx.) Small. 

 [Euphorbia ilfiitata Michx.] This weedy 

 species was found in 15 hill prairies. 



Anacardiaceae 



Rhus aromatica Ait. Fragrant sumac 

 was seen in 15 hill prairies, either in loess 

 or rocky soil. It was encountered also in 

 some wooded coves as well as in bluff-top 

 woods. 



Rhus aroiiialud var. arenaria (Greene) 

 Fern. This variety of the fragrant sumac 

 was found in sandy loess at Bald Bluff, 

 Balk, Bielema, and South Palisades. 



Rhus copallina L. Shining or dwarf 

 sumac was found in loess at Southwest 

 P'dgcmont, Challin Bridge, Fults, and 

 Phegle\'. 



Rhus glabra L. Smooth sumac was a 

 very frequent plant in the hill prairies 

 studied. It was observed on 33 rock and 

 loess prairie slopes. It grew in coves and 

 extended out on the spurs, or it grew in the 

 borders of the bluff-top woods and out in 

 the prairies as isolated individuals. In 

 some places it was very dense and formed 

 a thicket. In a few other places most of 

 the individuals in open groups were dead 

 or dying, a result possibly of fire, or of 

 competition by grasses, competition in- 

 tensified by summer drought. 



Rhus railicans L. Poison ivy, erro- 

 neously called poison oak, was very abun- 

 dant in woodlands adjacent to most of the 

 hill prairies. It was found at Principia 

 in loess and rock prairie. 



Aquifoliaceae 



Ilex decidua Walt. Possumhaw or 

 swamp holly, normally found in bottom- 

 land woods or on basal slopes of bluffs, 

 infrequently on shaded cliffs, was ob- 

 served in a cove at Phegley, 200 feel 

 above the adjacent bottomland. 



Celastraceae 



Celastrus scandens L. Bittersweet oc 

 curred in eight hill prairies that adjoined 

 woods. It occurred also in wooded cove; 

 near prairie. 



Rhamnaceae 



Ceanothus americanus L. New Jersej 

 tea, a plant of rocky woods, forest bor 

 ders, and glades, was observed in 12 loes 



