TEE PLORA 



Seven hundred and six species of flowering plants and ferns have 

 "been collected on the Patuxent Research Refuge "by the writer, including 

 93 grasses, 61 sedges, 79 composites, 46 trees, and 55 shrubs and woody 

 vines* All but' 7 of the species are included in Hitchcock and Standley's 

 1919 Plora of the District of Columbia and Vicinity (or its 1930 Supple- 

 ment by McAtee) , which describes a total of 1771 species. This is a rich 

 flora considering that so many plants of the Washington region are re- 

 stricted to the Piedmont Plateau or to the Potomac River Valley. 

 A number of species' listed in the "District Flora" as occurring only on the 

 Piedmont Plateau have been fo\ind to be common on and in the vicinity of 

 the Patuxent bottoms. The Piedmont-derived soil and the continuity of 

 the bottom lands from the lower Piedmont Plateau through the Coastal 

 Plain help to explain this distribution. Although Sanguinaria canadensis 

 has been identified from growing plants on the refuge, it is the only species 

 in the following list that is not yet represented by one or more permanently 

 filed specimens. Possibly 100 additional species could be listed in 2 or 

 3 more years of collecting, but there arc not many common plants, with the 

 exception of certain composites, carices, .and panicums, that have been 

 overlooked. 



Lis t of Plants 



"West," "east," and "south" (W, E, and S, respectively), refer to 

 the three separately fenced tracts of the refuge. . Numbers in parentheses, 

 except as otherwise noted, refer to plants collected by the v/riter; identi- 

 fications other than those by the writer are so indicated. 



POLYPODIACEAE: 



Asplenium platyneuron (L. ) Oakes. — Occasional; W, S; hedgerows and 



former clearings, (5155) 

 Athyrium asplenioides (Michx.) Desv. — Occasional; W; terrace forest, 



T5248p 

 Sennstaedtaa. punctilobul a (Michx.) Moore. — Occasional; W, S; mostly 



terrace forest. (5438) 

 D ryoTjteri s cristata (L.) A. Gray. — Occasional; W; swamp forest. (5055) 

 D, hexa gon op tera~l Michx.. ) C. Chr. — Occasional; W; well-drained bottom- 

 land forest. (5310) 

 D. marginal is (L.) A. Gray. — Rare; W, S; terrace and slope forest. 



(5054) 

 D. noveboracensis (L. ) A. Gray. — Common; W, S; terrace forest. (5423) 

 R • splnulosa (Muel 1 . ) Kun t z e , var . intermedia . ( Muhl , ) Un de rw , — Oc c a- 



sional; W; terrace forest. (5056, det. W. R. Maxon) 

 D. thelypteris (L, ) A. Gray. — Occasional; W, E, S; open shrub swamp. 



(5501) 

 Onoclea sensibilis' L. — Occasional; W, E; wet meadow. (5586) 

 Polys tichum acrostichoides -(Michx.) Schott. — Occasional; W, E, S; 



terrace and slope forest. (5445) 

 Pteridium latiusculum (Desv.) Maxon. — Common; W, E, S; terrace (rare), and 



slope and upland forest. (5608) 

 Woodwardia areolata (L.) Moore. — Common; W, E, S; swamp forest. (5500) 

 W. virginica (L. ) Sm. — Rare; W; shrub swamp. (5503) 



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