472 BOTANICAL GAZETTE [DECEMBER 
leaves and stems die simultaneously, as in ephemerals, most annuals and bien- 
nials, and monocarpic plants generally. Leaffall is absent in most herbs, and 
present in most woody plants, especially in those which require much light in 
connection with bud development; this light is secured when the leaves have 
fallen. Leaffall is less pronounced or even absent in woody plants whose buds 
never lack sufficient light. Leaffall occurs in woody plants after injury or death, 
or when they develop in conditions where ] functions cannot be performed.— 
H. C. CowLes. 
CHANDLER?S has examined the “seedlings” of a number of ferns, mostly 
belonging to Polypodiaceae. In nearly all the cases studied a protostele was 
found to pass into the condition of siphonostele or dictyostele by the appearance, 
inside the xylem of the central cylinder, first of phloem, then of endodermis, and 
lastly of fundamental tissue which communicates at the foliar gaps with the 
fundamental tissue of the cortex. Usually several leaf traces are given off before 
the central cylinder incloses fundamental tissue, and at this level the core of the 
central cylinder consists of phloem. The writer concludes that “the primitive 
type of vascular system in the ferns is a solid rod of vascular tissue, which may 
be a solid xylem strand surrounded by phloem, or an amphiphloic strand.’”’ The 
writer follows JEFFREY in considering the parenchymatous pith of the central 
cylinder to be of the same morphological nature as the cortex; curiously enough 
he hesitates to apply this generalization to certain species of Osmunda, though 
he considers the rule to hold wen me O. oe The rae of the inves- 
tigation seem to confirm the view that tem resembles 
what has probably been its phylogeny. The disies ee a solid to a tubular 
central cylinder is attributed to the necessity for an efficient attachment of the 
leaf traces. The mode of origin of double leaf traces in several genera is care- 
segs senna = well represented in the plates accompanying the paper.— 
M. A. Car 
Within Ge past few years, Dr. Lujo Apamovié has published a number of 
papers dealing with the plant geography of Servia. A recent contribution?4 has 
to do with the sand steppes of that country. This is not a single unified forma- 
tion, but comprises a group of formations, similar in ecology, distribution, and 
life-history. Meadows contain hygrophiles, grasses which form close mats, 
and there are but few annuals or coarse herbs; steppes, on the contrary, contain 
xerophiles, and there are many annuals and coarse herbs; heaths are in places 
where soil and air are wet, and they contain half-shrubs, among which a single 
species often dominates. The life-history of the sand steppes is interesting. 
Sand commonly encroaches on vegetation, but the reverse is the case in wet years. 
3 CHANDLER, S. E., On the arrangement of the vascular strands in the “seed- 
lings” of certain poke nee ferns. Annals of Bot. 19:365-410. pls. 18-20. 
1995. 
24 ApAMOvic, L., Die Sandsteppen Serbiens. Engler’s Bot. Jahrb. 33:555-617- 
1904. 
