FLORA OF WASHINGTON AND VICINITY. 23 



distance above the last, has a more elevated central portion, and a simi- 

 lar vegetation. Here was found on our first visit, and also on subse- 

 quent ones, Delpliinium tricorne, and for this contribution to the Flora 

 Columbiana it was christened Larkspur Island. The fourth of these 

 islands is in many respects similar to the two last described, and upon 

 it stands the only indigenous specimen of Acer saccharimim (q. v. infra) 

 yet found here. It has therefore been approi^riately named Sugar- 

 Maple Island. Erytlironium alhichim, Trillium sessile, Jeffersonia di- 

 phylla, and similar species abound on all these islands, while on the 

 Larkspur Island, besides the Delphinium, has also been found Fhacelia 

 PursMi. The beauty of these natural flower-gardens in the months of 

 April and May is unequaled in my experience. The light and rich allu- 

 vial soil causes the vegetation to shoot up with magic rapidity at the 

 first genial rays of the vernal sun, and often the Harbinger of Si)ring 

 {Erigenia bulbosa), true to its name, will greet the delighted rambler 

 in late February or early March. 



The opposite or Virginia side of the Upper Potomac consists entirely 

 of bold bluffs, interrupted by deep ravines, often containing wild tor- 

 rents and dashing cascades. Here the flora, though less rich and 

 varied, is also characteristic and interesting, and embraces among 

 other rare things Rhododendron maximum, Iris cristata, Scutellaria sax- 

 atilis, Pycnanthemum Torreyi, Solidago rupestris, and S. Virga-aurea, var. 

 humilis. 



On the Maryland side, and a mile above the uppermost point thus far 

 mentioned is the Cabin John Eun, which the botanist celebrates more 

 for its Walking Fern [Camptosorus rhizophyllus) than for the world- 

 renowned arch that spans it. 



The next most prolific source of interesting plants is the region of the 

 C-reat Falls. The collecting grounds begin a mile or more below, at 

 Broad Water. On both sides of the canal the country is excellent, 

 rocky and wooded, with stagnant pools and sandy hillocks. On these 

 rocks grows Sedum telephioides, and near Sandy Landing are found Vitis 

 vulpina (q. v.), Arahis patens, A. hirsuta, and Triosteum angnstifolium. In 

 the pools have been found Garex decomposita, Potamogeton hyhridus, and 

 P. panciHorus, while on a rocky headland a large " water-pocket" has 

 yielded us our only si)ecimen of the white water-lily [Nymphcea odorata). 

 Cratcegus parvifolia, Bumex verticillatus, Steironema lanceolatum, and 

 last, but not least, Nasturtium lacustre, have also rewarded my re- 

 searches in this singular and rather weird region. 



