ANATOMY OF THE ROOTS OF PALMS. 473 
on either side by a phloem-group. Both large and small ares are externally bounded by 
an endodermis which dips into the gaps between the ares and is lost in the common 
ground-tissue. 
(40) OREODOXA REGIA, H. B. & K. 
There is a thin-walled limiting-layer, followed by elongated lignified pitted elements. 
The cortex is largely parenchymatous, but widespread lignification obtains, and a special 
ring of lignified elements, two or three cells in thickness, surrounds the endodermis. The 
air-spaces are small and extremely irregular. The endodermis is of the ordinary lignified 
type; xylem V's are frequent and also more complicated arrangements, as shown in the 
accompanying woodcut (text-fig. 13). There is generally only one ring of large internal 
Fig. 13. 
206 50809 
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vessels, which are peripherally placed. The xylem and phloem are embedded in a fibrous 
zone of very densely packed, thick-walled, and lignified elements. There is centrally a 
pith, through which run one or more sclerenchymatous strands with central vessels. 
(41) Howza Forsteriana, Becc. 
A. Specimen from Glasgow.—Limiting-layer and tegumentary layer normal, the latter 
containing much mucilage. The inner parenchymatous cortex contains irregularly 
arranged fibres, not usually united into bundles. In the internal portion of the 
cortex rather large air-spaces occur, together with bundles of fibres. The endodermis 
is lignified and the pericycle is generally one- (locally two-) layered. The sclerenchy- 
matous zone contains the xylem and phloem as usual. The large vessels of the interior 
are so arranged that each protoxylem-group has its own large vessel (occasionally a V is 
formed). This leads to close packing of the large vessels, which are consequently radially 
compressed into an elliptical shape. The phloem extends centrally to a greater extent 
than in the majority of roots. In the centre there is a large parenchymatous pith. 
B. Specimen from Ceylon.—The cortical air-spaces are here much smaller and the 
fibres more generally occur in bundles. The vascular elements are all peripherally placed 
in the sclerenchymatous zone. Where no large internal vessel abuts on the space between 
two xylem-groups, the intervening phloem-group may extend for a considerable distance 
‘centrally. (Text-fig. 14.) This is the only root in which this character has been seen so 
Fig. 14. 
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well developed. The large pith contains small air-spaces, and ina large root one or more 
free sclerenchymatous strands may occur, each with its central vessel In large roots 
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