HARPER: BOTANICAL CROSS-SECTION OF MissiIssippr1 397 
published lists of calciphile plants for particular regions, and 
in temperate eastern North America certain plants, mostly trees, 
have become by common consent, as it were, accepted as indicators 
of calcareous soils. Dr. Hilgard lists quite a number of these in 
each of his books, and even goes farther and distinguishes dif- 
ferent forms.of the same species characteristic of different kinds 
of soil. But none of these writers seem to mention any characters 
which their calciphile plants have in common, so that if a person 
totally ignorant of mineralogy should travel around the world he 
could identify the limestone regions only by knowing the individual 
species which have been listed as calciphile; and the flora changes 
almost completely every thousand miles or so in temperate 
regions, 
As a matter of fact, the supposed lime-loving trees listed by 
Hilgard and others in this country do have some characters in 
common. They are all deciduous except the cedar (and I have 
recently shown that that is not necessarily calciphile*), and many 
of them have durable dark-colored heart-wood, thin leaves, and 
large seeds. But trees with similar characters, and indeed most 
of the same species, can be also found in many places where the 
soil is poor in lime or at least not commonly regarded as cal- 
careous, and associated with other species which have not been 
hitherto regarded as calciphile. Coville in his work in Arkansas 
a quarter of a century ago found that the difference in the vegeta- 
tion of sandstone and limestone areas in close proximity was more 
quantitative than qualitative; i. e., the species were nearly the 
same, but their relative abundance differed considerably in the 
two areas.t : 
Comparatively few observations on calciphile vegetation in 
tropical and cold-temperate regions seem to have been made. In 
Schimper’s Plant Geography less than a page (380) is devoted to 
the effects of lime on vegetation in the tropics, and he believes 
its influence to be less there than in temperate regions. In ex- 
treme southern Florida, including the Keys and most of the main- 
land south of Miami, the rock is nearly all limestone,{ and there 
* Torreya 12: 145-154. I9gI2. 
t See Arkansas Geol. Surv. Rep. 1888!: 246-247- 18 . 
tI have no analyses of the mainland rock, but that a the Upper Keys is sai 
to be over 90% calcium carbonate. 
