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R. J. HARYEY-GIBSON AND ELSIE HORSMAN ON 
very abrupt endings. In the very few cases where secondary rays have been found, 
they are by no means uniform in their occurrence, a transverse section showing 
perhaps only three or four secondary rays to a large number of primary ones. The 
presence of secondary rays is always associated with wide bundles and narrow 
primary rays. 
The pith in the majority of cases is heterogeneous, as in B. vulgaris , L. Many 
species show solitary klinorhombic -crystals of calcium oxalate in addition to starch 
in the peripheral cells, e.g. B. aquifolium, Pursh., B. stenophylla x hort., B. Jame- 
soni, Lindl., B. empetrifolia, Lam., B. Darwinii , Hook. 
Some species show a pith sclerotic throughout, but here also the central cells 
are often larger than the peripheral ones, e.g. B. Darwinii , B. angulosa. 
The general plan of structure of the stem in Berberis ( Mahonia ) aquifolium, 
Pursh., is the same as that of other species ; a sclerotic pericycle and cork cells with 
wide lumina are present ; the xylem shows the same predominance of lignified 
fibres and the same broad primary medullary rays. The bordered pits have round 
apertures, as in B. angulosa , in contrast to the slit-like pits most frequent in the' 
genus. No lignified fibres occur in the bast. The pith is sclerotic throughout. 
Summary of Anatomical Characters of Berberis. 
1. There is a continuous’ sclerotic ring of pericycle fibres, similar to that present 
in the Flacourtiacese. 
2. Cork cells with remarkably wide lumina occur, as in some Menispermacese. 
3. Bast fibres occur in tangential rows in the secondary phloem, agreeing in form 
and arrangement with those of Lauracese and some Magnoliacese. 
4. The xylem is composed chiefly of strongly lignified fibres with occasional thin 
transverse septa, as in Lauracese and Flacourtiacese. 
5. The largest vessels and some of the tracheids exhibit bordered pits with slit- 
like apertures, while most species show a combination of bordered pits and spiral 
thickenings. 
6. Very little parenchyma occurs in the xylem, in which particular it again 
agrees with that of the Menispermacese. 
7. Broad lignified primary medullary rays are characteristic of the genus, with 
only very occasional secondary rays. In the Menispermacese the rays are similar 
in all respects, save that some cells in the broad rays may not be lignified. 
8. The pith is usually heterogeneous, though in some species the cells are 
sclerotic throughout. Heterogeneous pith also occurs in Magnoliacese, some 
Lauracese, and Menispermacese. 
9. The phloem consists of sieve tubes, companion cells, phloem parenchyma, and 
bast fibres ; the two former occur principally in the primary phloem, while the 
secondary phloem consists mainly of parenchyma and bast fibres. 
