530 Rivett . — The A natomy of Rhododendron ponticum, L, } and of 
side there is also a higher proportion of vessels to fibres than there is on the 
narrow side. 
Ilex Aquifolium. 
General Morphology . The Holly {Ilex Aquifolium ) is a fairly rapid 
grower, making shoots up to 30 cm. long in a single season. The year’s 
growth is simple, such as is found in most evergreen trees. There is 
a terminal winter-bud, bearing 5 or 6 spirally arranged scales. When the 
young shoot elongates in the spring, the scales fall off, but two or three 
transitional leaves are borne between the first elongated internodes, before 
the true foliage leaves appear : of these, fifteen may be borne in a single 
season. The internodes show the usual gradations in a year’s growth — i.e. 
the longest are in the middle and the shortest towards base and apex. 
The transitional scale-foliage leaves fall during the first season, leaving 
a narrow encircling scar similar to that of the bud-scales. The foliage 
leaves may persist for four or five years, but usually some of the lower ones 
in each year’s growth fall off in their second and third year. Buds are 
found in the axils of the scale leaves and the foliage leaves, but it is only in 
the upper regions of a year’s growth that they normally develop into lateral 
branches. The shoots are soft and immature at the end of the first season, 
but they harden and increase in girth in successive years. The growth 
from year to year is monopodial, as it is the terminal winter bud which 
develops at the beginning of each season. 
Material. For this investigation the material consisted of straight 
twigs of three, four, or five years’ growth, cut in July 1919. The twigs are 
figured and lettered in Diagram II. From this it can be seen that the 
twig F, of total length 5a cm., consisted of three successive annual shoots — 
a 1916 shoot of 15 internodes, 22 cm. long : a 1917 shoot of 13 internodes, 
19*6 cm. long: a 1918 shoot of 14 internodes, 10*4 cm. long — and an 
abortive 1919 shoot. Thus the twig exhibits four annual rings at the base, 
three in the middle, and two at the upper end. The scars of the winter-bud 
scales are taken as indicating nodes and are reckoned in the total internodes 
numbered from base to apex. The shoot G, of total length 5s cm., con- 
sisted of four successive annual shoots : the oldest, dating from 1915, shows 
five annual rings: the topmost, dating from 1918, shows two annual 
rings, there being again no one-year-old shoot, owing to abortion 
or accident in the early spring of 1919. The shoot H, of total length 
63 cm., shows four successive annual shoots, including the uppermost still 
active in July 1919. The shoot K, showing five successive years’ growth, is 
the longest and stoutest of the set and reaches a length of 77 cm. The 
shoot L shows great length, 58 cm. — considering that it is made up of three 
annual shoots only. The internodes are particularly long, straight, and well 
developed. The shoot M, of four years’ growth, reaches a length of 73 cm. 
