66 
GENERIC DISTINCTIONS IN PLANTS. 
fibrose, tereted, or testiculate ; but as access cannot always conveni¬ 
ently be bad to this part of the plant, it is better to fix the specific 
distinction on some other circumstance equally constant, if it will 
admit of it. 
The trunk often furnishes a sure mark of distinction. Thus in 
Hypericum, Convallaria, and Hedysarum, there are many species 
distinguishable by the angles of the stem ; in Lupinus, the species 
are not to be easily known, except by the same part being simple, 
compound, or decompound; in the species of Eriocaulon, the most 
remarkable difference is in the culmus, which is quinquangular, hex- 
angular, decangular, &c. in Tyrola, some species are distinguished 
by a triquetrous scapus; in Citrus, the orange (Aurantium) is dis¬ 
tinguished from its congeners, by its petioles, which are winged, or 
increased bv a membrane on each side. 
%/ 
The leaves exhibit the most natural, and also most elegant specific 
differences; these will be amply treated of in a future number. 
The fulcra are generally a good mark of distinction, and must be 
carefully attended to by the botanist, for the determination of the 
species. Thus aculie are remarkable in Rubus ; spines, in Prunus; 
bractea in Fumaria, to which must be added the Coma, which is a 
bushy head composed of bractea of a larger size, and terminate the 
stem, as in Lavendula and Salvia. 
Glandules furnish the essential mark in Acaeia, and other Genera, 
which it would be almost impossible to distinguish without being ac¬ 
quainted with that part. In Amugdalus, they are found on the ser- 
ratures, at the base of the leaves, which distinguish it from Persica ; 
in Passiflora, on the back of the leaves; and the species of Urena 
could never have been fixed without examining the glandules of the 
leaves. 
Stipulea are of great consequence in many extensive genera, where 
the species are liable to confusion ; thus in Melianthus, they are so¬ 
litary in one, and in pairs in another species. 
Hybernacules afford certain specific differences. That gems or 
buds often differ greatly in the same genus is proved by Rhamnus, 
by the various species having all a difference in their buds; and in 
that extensive and intricate genus, salix or willow, the species are by 
the structure and foliation of the buds distinguished with great cer¬ 
tainty. Bulbs also afford real distinctions, as in Scilla, where they 
are almost the only distinction, and by their situation in the axilla 
of their leaves they determine Lilium, Dentaria, See. 
Inflorescence affords the truest, and in some genera the most beau¬ 
tiful distinction; thus in Spiraea,' the flowers are in some species 
