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VEGETATION OF SOUTH FLORIDA 



in the sand-pine forest. Of the plants with a striking xerophytic structure 

 may be mentioned Opuntia austrina Small, with flat joints, two feet tall, and 

 the Spanish-bayonet, Yucca aloifolia L. 



The herbaceous plants of the sandy soil as a third layer grow out of a leaf 

 litter two inches thick which covers the forest floor beneath the pine trees. 

 The two most common herbs collected by me at West Palm Beach on August 

 10, 1911, were Polygonella polygama (Vent.) A. Gray and Afzelia pectinata 

 (Pursh.) Kuntze, while on some waste material at the edge of the forest grew the 

 balsam-apple, Momordica charantia L. The earth-star, Geaster sp., was found 

 as an element of the fourth or ground layer of the forest. The white sand of 

 the rosemary scrub formation is either covered with pine needles and other 

 litter, or with plant growth. Here and there are bare stretches of white sand 

 with several gray lichens forming part of the fourth layer. Three species of 

 Cladonia, determined by Prof. Bruce Fink, are found. They are Cladonia 

 sylvatica (L.) Hoffm., which grows in rounded, spongy cushions, Cladonia 

 alpestris (L.) Rabenh., a fine gray lichen, and Cladonia leporina Fr., a coarse 

 gray lichen. 



The vegetation of these ancient sand dunes is essentially xerophytic, be- 

 cause the water, which falls as rain, rapidly percolates through the sand. The 

 radiation of the sun is also quite intense, especially the noonday glare, and the 

 wind action must be considerable, as the pine trees incline inland in some 

 places at considerable angles. The soil of these sand hills is well adapted to 

 the growth of the pineapple and some of the largest pineapple plantations in 

 Florida are found in this region. A few plantations are of such size that small 

 cars, drawn by mules and men on wooden tracks are used to collect the fruit 

 from distant parts of the sandy fields. The pineapple is the crop for such 

 areas and its cultivation is being extended rapidly, so that in time the natural 

 forest of sand pine and associated vegetation will be cleared to make room 

 for pineapple fields. 



SLASH-PINE (PINUS CARIBAEA) FORMATION 



The exposures of oolitic limestone, which we have named and described 



in the section on Geology, the Miami-Key West oolite, are covered in the 



main with the slash-pine tree, Pinus caribaea Morelet, which also extends much 



farther north on other types of soils. The outcrops of oolotic limestone extend 



