FREE INSTITUTE OF SCIENCE 
VEGETATION OF SOUTH FLORIDA 
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vegetation of the outer thicket (Plate Т, Fig. 1) as well as dwarfed trees. 
The most prominent of these trees and shrubs collected by me in the outer 
thicket on the Gulf side of Sanibel Island June 13, 1912, were Pithecolobium 
unguis-cati (L.) Benth., Jacquinia keyensis Mez. (in flower and fruit), Ra- 
panea guianensis Aubl. (in fruit), Forestiera porulosa (Michx.) Poir, Meta- 
stelma scoparium (Nutt.) Vail, Lantana involucrata L. (in fruit), L. ovatifolia 
Britton (in fruit), while the trees and shrubs are draped with Virginia-creeper, 
Parthenocissus (Ampelopsis) quinquefolia (L.) Planch and poison-ivy, Rhus 
radicans L. 
The thicket proper is an impenetrable mass of trees, shrubs, palms, and 
lianes, which bar the progress of the botanist. The shade is so dense that 
practically none of the herbaceous plants of the sandy beach can grow, and 
therefore the forest floor is bare, or is characterized by litter consisting of 
dead leaves of the palmetto, seaside-grape, and other overhead trees, but forest 
humus in the sense that that word is used in the deciduous forests of our 
northern states does not exist. The height of the tallest trees, which include 
Sabal palmetto (Walt.) R. & S., varies from 15 to 20 feet. The papaw, Carica 
papaya L., may be included as an introduced element of this thicket, which is 
without pine trees, and extends across the island to the bay shore. The outer 
thicket of the bay side of the island is characterized by the presence of such 
trees and shrubs as Suriana maritima L., Bursera simaruba (L.) Sarg., Jac- 
quinia keyensis Mez., Psychotria undata Jacq., and the climber Melothria 
pendula L. 
Physiognomically the thicket vegetation of Sanibel Island is similar to that 
described for Anastasia Island, but from the top of Sanibel light-house the 
impression that a botanist gets is a bushland of taller trees of a brighter green 
aspect, not so gray-green as the scrub of Anastasia Island. Perhaps owing to 
the more level surface and the more uniform crowns of the trees, the undulation 
of the forest cover is less noteworthy than on Anastasia Island. 
Across San Carlos Bay, on the mainland at Punta Rassa, the thicket 
vegetation is taller and of larger trees. The forest here is not so uniform, 
because it is broken by salt lagoons, or flats, where the mangrove vegetation 
forms the exclusive growth, but on the higher ground the shore thicket is well 
developed and blends with the beach vegetation on the water side and with 
the forest proper on the landward side. The more important and conspicuous 
elements of this thicket collected by me on June 14, 1912, while waiting for 
