134 Curtis , — The Anatomy of the Six Epiphytic 
S . adversus : occurs in the lowland districts of North and South 
Islands, Stewart Island, and the Chatham Islands, but is not common. 
Earina mucronata , Lindl. Bot. Reg. sub t. 1699. 
Stem creeping. Branches numerous, 1-3 ft. long, slender, simple, 
pendulous or rarely erect, smooth, compressed and two-edged, spotted. 
Roots long, thick or slender, with smaller branch roots at intervals. Leaves 
3-6 in. long, in. broad, narrow linear, acuminate, flat, smooth, thin but 
coriaceous, very finely striate. Panicle terminal, many-flowered. Flowers 
rather distant, \ in. diameter. Sepals and petals pale yellow, lip darker 
with brownish orange spot at the base. 
Roots and rootlets are a dull white colour except near the tips where 
the velamen has not yet become filled with air and the green of the cortex 
is still visible. The central cylinder contains from eleven to thirteen 
alternating groups of xylem and phloem, and is surrounded by a thin- 
walled cortex occupying the greatest portion of the root (PI. VII, Fig. 1). 
Outside the cortex lie the exodermis and a velamen of several rows. 
Root-hairs are frequently present, especially in flattened specimens where 
the substratum adjoins. When the velamen consists of four rows, the three 
outer are somewhat similar to one another. In transverse section their 
cells are practically isometric ; the thickening strands are reticulately 
arranged, but have a general tangential direction. In longitudinal section 
the cells are elongated and the strands run more or less parallel to the long 
axis of the root. The innermost layer of the velamen consists of large cells 
tangentially elongated in transverse section ; the strands on all their walls 
are radial. Cutinization of walls and strands occurs throughout the 
velamen and is especially heavy in the cells near the exodermis. The 
latter consists of a single row of cutinized elements whose continuity is 
broken by the occurrence, at intervals of usually four cells, of smaller 
passage cells with cellulose walls. The thickened cells are somewhat com- 
pressed tangentially, but are much elongated in the longitudinal direction. 
Thickening and cutinization occur on their radial and external tangential 
walls only. The former are finely striated. The two walls forming the 
angle on the cortical side are of cellulose. In longitudinal section passage 
cells alternate with cutinized cells. The denser protoplasmic contents and 
large nuclei of the former present a contrast to the thin protoplasmic lining 
and small nuclei of the latter. 
The cells of the cortex vary in depth from eight in the smaller branches 
to twenty or more in the principal roots. The unusual thickness of 
some roots is due chiefly to a greater depth of cortex, but a few additional 
rows in the velamen may occur at the same time. Two small cells always 
bound the inner walls of the passage cells. The largest cells lie in the cen- 
tral portion of the cortex, while they diminish in size towards exodermis and 
