FREE INSTITUTE OR SCIENCE 
VEGETATION OF SOUTH FLORIDA 
181 
condition of the soil. The physiography of the islands is less diversified than 
that of the mainland of peninsular Florida. The difference in the number of 
species in favor of the Miami region is 251 species and in genera 114. If we 
compare* the families of seed-plants in the Miami flora with those given in the 
last edition of Gray's Manual (Robinson and Fernald, 1908), we discover that 
the following families are represented in the Miami flora and not in Gray's 
Manual: Cycadaceae, Cymodoceaceae, Arecaceae, Alpiniaceae, Cannaceae, 
Marantaceae, Casuarinaceae, Petiveraceae, Batidaceae, Allionaceae, Mal- 
pighiaceae, Surianaceae, Burseraceae, Meliaceae, Dodonaeaceae, Buettneriaceae 
Turneraceae, Papayaceae, Cassythaceae, Punicaceae, Terminaliaceae, Myrta- 
ceae, Rhizophoraceae, Theophrastaceae, Ardisiaceae, Dichondraceae, Ehre- 
tiaceae, Avicenniaceae, Olacaceae, and Brunnoniaceae. The following families 
of flowering plants represented in the region covered by the new Gray’s Manual 
are absent from the Miami district: Dioscoreaceae, Betulaceae, Calycan- 
thaceae, Sarraceniaceae, Saxifragaceae, Hamamelidaceae, Platanaceae, Em- 
petraceae, Violaceae, Araliaceae, Diapensiaceae, Valerianaceae, and others 
not of great importance. Sedges of the genus Carex are entirely absent in 
the Miami region. When we compare the Miami flora with that of the Florida 
keys by the same author and, therefore, strictly comparable as to the family 
limits, we discover that in passing from the mainland to the islands a number 
of families drop out. Such are Juniperaceae, Naiadaceae, Scheuchzeriaceae, 
Araceae, Juncaceae, Liliaceae, Haemodoraceae, Alpiniaceae, Cannaceae, 
Marantaceae, Burmanniaceae, Saururaceae, Piperaceae, Salicaceae, Fagaceae, 
Alsinaceae, Caryophyllaceae, Ranunculaceae, Magnoliaceae, Nympheaceae, 
Droseraceae, Aquifoliaceae, Cistaceae, Ericaceae, Vacciniaceae, Menyan- 
thaceae, Polemoniaceae, Campanulaceae and Lobeliaceae, 29 families in all. 
Our surmise as to the absence of freshwater conditions on the Florida keys is 
corroborated by the absence of plants of the families Naiadaceae, Scheuch- 
zeriaceae, Nympheaceae, Droseraceae and Menyanthaceae. We discover also 
in the flora of the Florida keys the absence of oaks, huckleberries, ranunculace- 
ous plants, magnolias, buttonbushes (Cephalanthus), elders (Sambucus) and 
species of the genera Carex and Scirpus. There is only one golden-rod (Soli- 
dago) and three asters on the Florida keys. 
* The comparison cannot be made exactly, because of the different views of the authors on the 
matter of family limits. However, the comparison is made as accurately as consistent with the dif- 
ferent interpretations of family names and limits. 
