10 ILLUSTRATION'S. 



• 20A. Showy orchis (Orchis spectabilis) . Widely distributed in rich woods in 



late spring, but not abundant. Flowers pink and white. 

 20B. Moccasin flower (Cypri.pedium acaule). A characteristic plant of sandy 



pine woods in May, the saclike lip rosy purple, mottled. 

 21. Lizard's-tail (Saururus cernuus), in a swamp near Dyke. A characteristic 



summer marsh plant with white flowers. 

 22A. Pin oak (Quercus palustris) in May, the leaves partially developed. The 



decurved lower hranches are characteristic of this species. 

 22B. Red oak (Quercus maxima) in May. 



23. White oak (Quercus alba) in May, a last year's growth of Andropogon 



elliottii in foreground. 



24. Yellow pondlily (Nymphaea advena) in shallow water near Dyke. Abun- 



dant in the marshes of the Eastern Branch and the lower Potomac. 

 25A. TIepatica (Ilepatica americana). Common in rich woods in March and 



April. Our earliest showy spring flower. 

 25B. Cream violet (Viola striata). Low woods along the Potomac in April 



and May. 



26. May-apple (Podophyllum pcltatum), common in rich woods in spring; 



flowers white. Below is the three-leaved stonecrop (Sedum ternatum), 

 frequent in rocky woods; flowers white. 



27. Sassafras ( Sassafras varii/o Hum) , as it occurs along old fence rows in the Oxon 



Run valley. 

 28A. Bloodroot (Sanguinaria canadensis); common in rich woods in March 



and April. One of our earliest spring flowers; petals waxy white; 



juice of plant orange-red. 

 28B. Twin-leaf (Jeffersonia diphylla); rich woods on islands of the Potomac 



in April. Leaves split into two equal parts; flowers white. 

 29A. Dutchman's breeches (Bikuhulla cucullaria). Rich woods along the 



upper Potomac in April; flowers white, tinged with pale yellow. 

 29B. Squirrel corn (Bikuhulla canadensis) . Resembling Dutchman's breeches 



but less common ; flowers white, tinged with pink. 

 30A. Pepper-root (Dentaria Jaciniata). Moist woods in April and May, the 



flowers white or pinkish. 

 30B. Saxifrage (Saxifraga virginiensis) . Common in rocky woods in April; 



flowers white. 

 31A. Wild strawberry (Fragaria virginiana). Common in fields and open 



grassland in May; flowers white. 

 31B. Star chickweed (Alsine pubera). Common in April and May in rocky 



woods, the flowers white. 



32. Goat's-rue ( Cracca virginiana) ; woods near Great Falls. Common in sandy 



or rocky woods in May and June. 



33. Black locust (Robinia pseudo-acacia) in May, just as the leaf buds are open- 



ing. An abundant, probably naturalized tree with handsome racemes 

 of white fragrant flowers in early summer. 

 34A. Squaw-root (Conopholis americana). Rich woods in May. A brownish 



root parasite, four to eight inches tall. 

 34B. Prickly pear (Opuntia vulgaris), on rocks at Plummers Island. This 

 specimen shows the fruit; the yellow flowers appear in June. Our 

 only native cactus. 

 35. Flowering dogwood (Cornus fiorida). A small woodland tree, the white 

 petal-like bracts conspicuous in the spring before the leaves appear. 



