Elements of probably neotropie origin. 229 
Juniperus (Sabina) barbadensis L.(**) 
Cyclospathe Northropii Cook. 
Pseudophoenix Sargentii Wendl. 
Thrinax argentea Lodd. (= Cocco- 
thrinax jucundaSarg.)(*+**) 
»  floridana Sarg. (*) 
Tillandsia balbisiana Schult. (*) 
» aloifolia Hook.(*+**) 
x fasciculata Sw. (*+8$) 
» utriculata L. (*+$) 
> recurvata L.(*}$) 
Agave sisalana Engelm. (**+) 
Swietenia mahagoni Jacq. (*+$**) 
Croton linearis Jacq. (*) 
Excoecaria lucida Sw. 
Hippomane mancinella L. (*+$**) 
Hypelate trifoliata Sw. (**) 
Gouania domingensis L.(**7) 
Rhizophora mangle L.(*+**) 
Bletia verecunda Sw. (* **) 
Epidendrum nocturnum L.(*+) 
Polystachya luteola Hook. (* **+) 
Coccolobis (Coccoloba) uvifera L. 
(1837 
Cassytha filiformis L.(*+**) 
Chrysobalanus icaco L.(*r$**) 
Caesalpinia (Guilandina) crista L.(**+) 
Byrsonima lucida Sw. (*) 
Bursera simaruba L.(*+**) 
Eugenia longipes Berg. (***) 
» monticola Sw. (* **) 
Conocarpus erecta L.(*+**) 
Avicennia nitida Jacq. (***+) 
Genipa clusiifolia Jacq. (***) 
Pectis linifolia L. (= P. Lessingii 
Fernald) (**) 
Canella Winteriana L.(**+) 
The distribution of plants in the southern extremity of Florida is an 
interesting confirmation of the historic development of a flora. Seven plant 
‚formations can be recognized, viz., ı the sea strand formation; 2 the mangrove 
swamp formation; 3 the everglade formation; 4 the prairie formation; 5 the 
savanna formation; 6 the pine-land formation; 7 the hammock-land formation. 
Historically, the sea-strand formation and the hammock-land formation are the 
oldest floristically speaking. The strand flora, consisting of such plants as 
Unzola paniculata, Panicum amarum, Ipomoea Pes-caprae, I. (Batatas) littoralıs, 
Jva imbricata, Cakile maritima, Agave decipiens (on tropic section), has existed 
as an element of peninsular Florida since the land was elevated above the 
sea and perhaps was derived from an earlier seashore flora, which existed 
along the shore of the mainland, or the coasts of the larger and more elevated 
sea islands. 
Nearly all the tropic species recently added to the flora of the United States 
were discovered in or about the hammocks, which are essentially duplicated 
by similar formations in the West Indies. The total area of the hammock- 
land is relatively insignificant, when compared with the pine-lands, yet the 
flora, as shown in the enumeration below is as rich, if not comparatively richer. 
Pinelands .... . 43 per cent. 
Hammocks. . . . 42 per cent. 
Everglades. . . . 15 per cent. 
The hammocks consist of isolated groups of hardwood trees, shrubs and 
vines. These hammock formations with an overlying soil, thicker than the 
pine-lands, due without doubt to the accumulation of vegetal detritus, vary in 
