ANATOMY OF THE GENUS SALICORNIA. 337 
the perennial species, and in the stem of S. Oliveri, the pericycle gives rise 
to a cork cambium, the activity of which produces externally a layer of cork 
seldom more than six cells in thickness; on its inner margin it may 
contribute slightly to the secondary cortex. A full account of the details of 
the cork development in Salicornia herbacea, Linn., is given by Leisering *, 
who traces its origin from the outer layer of the pericycle, the inner layer he 
regards as the seat of origin of the extrafascieular cambium. We are in 
agreement with these statements, but are unable to confirm his observation 
that the plant laeks leaves, for reasons which have been detailed already. 
Tue Ноот. 
The primary root is always diarch in structure, and has always a very 
well marked endodermis (Pl. 16. fig. 13). Even the youngest roots have а 
well formed aerating zone in the cortex ; this zone consists of a large inter- 
cellular space bridged over at intervals by long narrow trabeculz. 
The primary condition of the root is maintained for a very short time, 
and anomalous secondary growth begins even in the seedling root (РІ. 16. 
fig. 13). It is of exactly the same type as that previously described for 
the stem. 
AERENCHYMA. 
At the extreme base of the main stem in $. fruticosa, S. herbacea, S. pusilla, 
S. prostrata var. Smithiana, S. ramosissima, and S. gracillima, and at the base 
of the aerial shoots and on the rhizome of S. perennis, S. perennis, var. 
lignosa, and S. Oliveri, the secondary cambium gives rise on its outer side 
to an aerating tissue of more or less considerable extent. The roots of these 
species, especially the thicker ones, also show a similar formation. 
In S. pusilla, S. prostrata, and S. fruticosa the zone of aerating tissue is 
of small extent and consists of rounded parenchymatous cells with a great 
development of intercellular spaces. 
In S. perennis and 5. lignosa the basal segments of the lateral shoots show 
ithe beginning of the aerating cortex even before the fall of the foliar sheath 
has been accomplished. These two species show at this stage the aerating 
zone made up of rows of rounded cells, very regularly arranged, with inter- 
cellular spaces between each row. | 
At the base of the main stem and in the upper part of the main root of 
S. herbacea and 5. ramosissima the aerating zone reaches its maximum, and 
these two species are characterised by the possession of a spongy coating 
* Leisering, B.: “ Uber die Korkbildung bei den Chenopodiaceen,” Ber. d. deutsch. Ges. 
xvii. (1899) p. 951. 
