ANATOMY OF THE ROOTS OF PALMS. 461 
surrounds a central parenchymatous pith, which may be more or less lignified. In the 
smallest roots available for examination there were no fibrous strands in the medulla, 
but older portions showed all stages from a single fibrous bundle with its central vessel 
to sections in which nearly the whole pith is occupied by these strands, and instead of 2 
single vessel, two to six may be present in each strand, generally one large vessel 
accompanied by from one to five smaller ones. In some cases two groups of vessels may 
be found in one fibrous strand. 
(11) Licvata sprnosa, Thunb. 
Similar in all essential respects to L. gracilis. The central pith is occupied by fibrous 
strands enclosing several vascular elements and in some cases two groups of vessels are 
present in each strand. 
(12) Livistona INERMIS, R. Br. 
The limiting-layer is more or less lignified and consists of small regularly arranged cells. 
The outer cortex is made up of elongated lignified cells. The inner cortex is parenchy- 
matous, with very irregular air-spaces and elongated, lignified, pitted cells. 
The cells of the innermost portion of the cortex are tangentially compressed, and 
among these are many densely lignified and extremely thick-walled stone-cells, some of 
` which are quite spherical. The endermic cells are lignified and much thickened, except 
on the outer tangential walls. The pericycle consists of one layer of lignified elements. 
A broad sclerenchymatous zone contains the xylem and phloem, and very definitely 
delimits the central pith, through which run fibrous elements, but no sclerenchymatous 
strands with vessels. 
(13) LIVISTONA ROTUNDIFOLIA, Mart. 
The cortex is parenchymatous with admixture of single lignified and pitted elements, 
but without fibrous strands. The air-spaces are irregular and comparatively small. 
The endodermis is of the usual lignified type. The pericycle is two cells in thickness, 
lignified and pitted. The sclerenchymatous zone is very densely lignified and thickened, 
giving to the central cylinder an extremely hard and solid character. No V’s are 
formed, and there are no vessels which cannot be definitely allotted to their respective 
protoxylem-group. 
There is a parenchymatous pith in which are present some lignified elements. 
(14) LivisTONA AUSTRALIS, Mart. 
Externally occur three or four layers of oblong, strongly lignified, much thickened and 
pitted cells, the lumina of which are almost obliterated. Then follows a broad zone of 
prosenchymatous elements, generally lignified, and then the parenchymatous inner cortex 
with small irregular air-spaces and lignified elongated cells scattered singly or in small 
groups; no fibrous strands occur. i 
The endodermis and pericycle are as in L. rotundifolia. There is a sclerenchymatous 
zone in which the xylem and phloem are embedded. The xylem frequently shows 
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