RICKER: BOTANipAL ACTIVITY IN DISTRICT OF COLUMBIA 487 



"whole and that of the crystal-molecules or unit cells of the lattice 

 may find expression in significant physical features, and there- 

 fore that both should be taken into account in the assignment 

 of crystals to symmetry classes, even though it may at times be 

 necessary to stat€ two different classes for the same crystal. 



BOTANY. — A sketch of botanical activity in the District of Colum- 

 bia and vicinity. — I. P. L. Ricker, Bureau of Plant 

 Industry. 



It would perhaps be difficult if not impossible to say who 

 started the first botanical work in the present District of Colum- 

 bia which, as nearly virgin wilderness, much of it swamp land,, 

 was ceded to the United States Government by the State of 

 Maryland in 1788. It would be much more difficult if we in- 

 cluded the part in Virginia ceded to the United States in 1789 

 and the area in Maryland surrounding the District. The fact 

 that Georgetown was settled late in the 17th century, although 

 not formally laid out until 1751, and Alexandria at least as 

 early as 1749, opens up a wide possibility. 



Rev. John Banister was probably the first to do much active 

 botanizing in Virginia, where he died about 1692. Ray (see 

 bibliography) makes no definite reference to his collecting near 

 the Potomac, although it is quite probable that he did some col- 

 lecting within the range of this flora. 



John Clayton came to Virginia in 1705. The list of his plants 

 published by Gronovius in 1743 shows that he collected Betula 

 nigra "a cataractis fluminis Potamoc," which might indicate 

 any one of several points from Little Falls to Great FaUs. 



George Washington began making improvements at Mount 

 Vernon soon after it came into his possession about 1759. It 

 is possible that a careful examination of his voluminous corre- 

 spondence and diaries at the Library of Congress, w^hich time 

 does not permit at present, might give more definite ideas as 

 to his plantings, many of which were doubtless introduced from 

 Europe. He did however plan for a Botanical Garden in the 

 District. Andre Michaux, the French botanist, visited Wash- 

 ington at Mount Vernon, June 19, 1786, on his way to New 



