188 BAR 
Ar’bor. A tree; a perennial plant, which rises toa considerable height, 
having a woody stem. Most treesspring froin seeds having two co- 
tyledons ; they are therefore called dicotyledonous plants. ‘The stems 
of such plants are said to be exogenous, that is, growing externally, 
new layers of wood being every year formed under the bark around 
the outside of the old wood. Palm trees are monocotyledonous 
lants; their stems are called endogenous, that is, growing internal- 
y, and pressing upon the outer coats, which become hard and com- 
act. ‘The ancient botanists divided plants into trees and herbs; 
ut this distinction is too vague to form the basis of classification. 
Arbusti’vus, (from arbustum, a shrub.) An ancient class of plants con- 
taining shrubs, as the myrtle, mock-orange, &c. 
Arcuate, (from arcus, a bow.) Bent like a bow. 
Arenarwus. Growing in sand. 
Argent‘eus. Silver coloured, 
Ard, Dry. 
A’ril, (arillus.) The external coat or covering of seeds which, dry- 
ing, falls off spontaneously. 
Aris’tate, (from areo, to be dried.) Awned, ending in a bristle. 
Aro’ides. So called from arwn, and forming a natural family of 
plants. 
Arms, (arma.) Offensive weapons. Plants are said to be armed, when 
they are furnished with prickles, thorns, &c. 
Aromatic. Sweet scented. 
Ar’row-form. Shaped like an arrow head, the hind lobes acute. 
Articulated. Jointed, as in the culm or stem of the grasses 
Arundtna’ceous, (from arundo, a reed.) Resembling reeds. 
Arvensis. Growing in cultivated fields. 
Ascending. Rising from the ground obliquely. 
Asperifo’lius. Rough leaved. 
Atten’uated. Gradually diminished or tapering. 
Auric’ulate. Having appendages resembling ears. 
Awi-form. Sharp at the point, and curved to one side. 
Awn. A short stiff bristle. 
Axil. The angle between a leaf and stem on the upper side. 
Axillary. Growing out of the axils: leaves are said to be axillary 
when they proceed from the angle formed by the stem and branch 
B. 
Bac’ca. Aberry. It is a pulpy pericarp, enclosing seeds without 
capsules. In the raspberry of a seed. 
Baccif'erous. Bearing berries. 
Ban/ner. The upper petal in a papilionaceous flower. 
Barb. A straight process armed with teeth pointing backwards. 
Barba‘tus. Bearded. j 
Bark. The covering of vegetables, consisting of several parts, as cu- 
ticle, cellular integument, &c. ‘The bark consists of as many layers 
as the tree on which it grows has years: a new layer being formed 
from the cambium every year, the newest layer of bark is called 
liber. 
Bar’ren. Producing no fruit; containing stamens only. 
