106 MORPHOLOGY OF PHILYDRUM LANUGINOSUM. 
terior, and thus opposite to the assumed sepals, a position identical with 
that of the same parts in the allied family Xyridacee. Hence, then, 
until further evidence of the affinities and structure of these singular 
plants affords us fuller information, we may assume that the corolla and 
a second row of stamens, internal to the existing one, are suppressed. 
Such a supposition accords with the evidence we now have, and is in 
perfect accordance with the due position of all the floral whorls, accord- 
ing to the law of alternation. 
The pollen grains of P. /anuginosum are roundish, and cohere in little 
groups of four. The lower end of the stem is globular, like the corm 
ofa Crocus. From its inferior surface proceed numerous simple root- 
fibres. This portion of the stem is chiefly cellular, the constituent cells 
being filled with large ovoid starch-grains. A cross-section of the up- 
per portion of the stem resembles at first sight that of an Exogenous 
rather than an Endogenous plant. The epidermis consists of one layer 
of rather thick-walled, oblong cells, with here and there a stoma formed 
by two oblong arcuate guard cells. Subjacent to the epidermis is a 
thick layer of parenchyma, the constituent cells being spheroidal or 
ovoid and containing chlorophyll. The cells are very loosely packed, 
so that the intercellular passages are numerous and irregular. Within 
this cellular layer is a complete zone of woody or bast tissue of con- 
siderable thickness, its outer boundary being nearly parallel in direction 
with the surface of the stem, the inner boundary here and there 
projecting inwards towards the'centre of the stem. Anatomically, 
this woody layer consists mainly of thick-walled wood cells with a very 
few fibro-vascular bundles interspersed here and there, especially to- 
wards the inner portion of the stem. Within this liber-like zone, is a 
cylinder of cellular tissue, the cells of which are spheroidal, much 
larger than those on the outer side of the bast zone; they contain no 
chlorophyll, and have very small intercellular passages. Traversing 
this portion of the stem are a few fibro-vascular bundles, consisting on 
the outer sides of wood-cells and on the inner of various forms of spi 
vessels and pitted ducts. Quite in the centre of each bundle may be 
seen a few thin-walled long cells—cambium cells? The sheathing 
leaves are of a spongy texture, with numerous large intercellular spaces 
crossed here and there by septa of radiating or star-shaped cells. 
M. T. MASTERS. 
