THE GENUS NOTOTRICHE. 205 
often of considerable systematic value. Humboldt noticed the peculiarity of these 
plants, that if the lamina is hairy on one side only, the hairs are always on the upper 
surface (cf. Pl. 29. fig. 12). As a general rule it is found that when hairs occur all 
over the leaf, the tomentum on the upper surface is more dense than, and is somewhat 
different in character from, that on the lower surface *. 
The tomentum is composed of stellate hairs which vary much in character throughout 
the genus, but a definite form of hair is perfectly constant for each particular species. In 
some cases the leaves are velvety owing to the close felting together of very small 
stellate hairs ; in others the tomentum is loose and shaggy, owing to the fact that the 
stellate hairs are large and borne on long stalks. Then, again, the stellate hairs may be 
sessile, but the rays of the star may be so long that the leaf appears to be covered by 
long silky hairs (e. g. W. sericea, &c.). 
In some species an almost peltate hair occurs, somewhat resembling that of Eleagnus, 
owing to the great number of the radiating arms or branches of the “ star.” Then, again, 
the arms of the hairs may be short or long, and this gives rise to different types of 
hairiness. Another group of species can be recognised where the stellate hairs have 
relatively few radiating arms, and yet a third group in which the radiating arms though 
very few (3-6), are long and silky. As these differing types of stellate hair may be 
combined with either the stalked or sessile condition it will be realised that a consider- 
able amount of variation in the type of tomentum exists in the genus. 
In the case of N. aretioides (Pl. 29. figs. 15, 16) the stellate hairs on the “ vagina” 
have become modified into definite spines with four to six arms and as the “ vaginæ "' 
are persistent on the stem long after the laminz have fallen, it seems likely that these 
spines are of some definite protective value to the plant. 
The Calyx.—The calyx may be hairy like the leaves, but as a rule, and especially in 
the species with densely aggregated leaves, only the protruding tips of the calyx-segments 
are felted with hairs, the rest of the calyx being glabrous since it is embedded among 
and protected by the leaf-bases. 
Within the calyx and situated at the base of each segment are five glandular patches, 
the nectaries, composed of a large number of short, erect, multicellular hairs (Pl. 30. 
figs. 2,3). The glandular hairs are very closely packed together, and consist usually of 
several tiers of four cells passing into a double row of cells and capped by a single 
dome-shaped cell (Pl. 30. fig. 4). As these nectaries are arranged alternately with the 
petals, they can be readily reached by an insect pushing its proboscis through the cleft 
between two adjacent petals just before their point of fusion with the staminal tube 
(PL. 30. fig. 2) Similar glandular nectaries have been found in the acaulescent species 
of the genus Malvastrum, A. Gray. 
The Corolla.—The corolla conforms to the common Malvaceous type, but two 
distinet forms are found in this genus. In some species there may be a fairly long 
corolla-tube fused with the staminal tube (from 2-6 mm. in length) and often covered 
with stellate hairs (Pl. 30. fig. 4); while in others the corolla-tube may be practically 
* In the acaulescent Malvastra the leaves are, as a rule, glabrous on the upper and hairy on the lower surface ; 
when hairs are present on the upper surface the lower is also hairy. 
