H Habitat—Site or place of growth. Hardwood—A collective term for broad-leaved trees, the wood of which may or may not be dense. Heartwood—The physiologically dead, central, usually darker colored portion of the tree trunk. Hybrid—A crossbreed of two species.
I Increment—Growth; increase. Incised—Divided into lobes separated by narrow or [acute] [sinuses] which extend halfway or more to [midrib]. Indehiscent—Applied to [fruits] that do not split open to discharge the seeds, remaining closed at maturity. Indigenous—Applied to plants that are native to a certain locality. Not introduced. Intolerant—Not shade enduring. Requiring sunlight. Involucre—A cluster of [bracts] subtending a flower.
L Lamina—The blade or flattened portion of a leaf. Lanceolate—Shaped like a lance; several times longer than wide, and growing to a point. Lateral—Situated on the side, as the buds along the side of the twig. Leaflets—One of the small blades or divisions of a [compound] leaf. Leaf-scar—The scar left after a leaf falls. Lenticel—A corky growth on young or sometimes older [bark], which admits air to the interior of the twig or branch. Linear—Line-like, long and narrow, with parallel edges. Lobed—Said of leaves that have the margins more or less cut or divided.
M Medullary—Pertaining to the [pith] or medulla. Medullary Ray—Radial lines of tissues crossing the growth of rings at right angles and extending into the [bark]. Midrib—The central or main rib or vein of a leaf. Monoecious—Bearing male and female flower parts in separate flowers on the same plant. Mucilaginous—Slimy or gummy when touched or chewed. Multiple fruit—A cluster of [fruits] of separate flowers crowded together and forming what appears to be a single fruit. Examples: mulberry, strawberry, osage-orange fruits.
N Naked—Said of buds without [scales], and seeds without a covering. Naval Stores—Refers to tar, turpentine, resin, etc. Node—A place on a twig where one or more leaves originate. Nut—A dry, 1-seeded, [fruit] with a hard [indehiscent] covering and encased partly or wholly in an [involucre] or husk. Nutlet—A small [nut].
O Oblique—Slanting, uneven. Uneven sided. Oblong—About twice as long as wide, the sides nearly parallel. Obovate—Reversed egg-shaped. Obtuse—Blunt Opposite—Said of leaves and buds, directly across from each other. Orbicular—Circular. Oval—Rounded. Ovate—Egg-shaped. Ovoid—Egg-shaped or nearly so.
P Palmate—Radiately [lobed] or divided from the [petiole]; hand-like as [leaflets] of buckeye. Panicle—A loose, irregularly [compound] flower cluster with flowers on [pedicels]. Pedicel—The support or stem of a single flower or [fruit] in a cluster. Peduncle—A primary flower stalk supporting a cluster of flowers or a solitary flower, later the fruit. A fruit-stem. Perennial—Lasting for more than one year. Persistent—Remaining after blooming, fruiting, or maturing. Petiole—The stalk of a leaf. Pinnate—Feather-like with leaflets on both sides of [rachis] or leaf stalk. Pistil—Seed bearing organ of flower. May consist of stigma, style, and ovary. Pith—The soft central part of a twig or stem. Pod—Any dry, one [chambered], [dehiscent] fruit. Pollen—The dust-like substance from the anthers of a flower. Pollination—The process of bringing the [pollen] of the male flower in contact with the stigma of the female flower. Pome—A fleshy fruit with a core, such as the apple or pear. Porous—With open tubes (through wood). Prickle—A sharp-pointed, needle-like outgrowth. Pubescent—With short, soft, down-like hairs. Pungent—[Acrid] or sharp to smell. Pyramidal—Shaped like a pyramid with the broadest part near the base.
R Rachis—The stalk supporting the [leaflets] of a [compound] leaf. Resin-ducts—A passage for the conduction of resin found in the leaves and wood. Ring-porous—Said of wood which has pores of unequal size, the larger ones being found in the spring wood and the smaller ones in the summer wood.
S Samara—An [indehiscent] winged [fruit] such as that of maple. Sapwood—The recently formed, usually light colored wood, lying outside of the [heartwood]. Scabrous—Rough, with stiff, bristly hairs. Scales—The small, modified leaves which protect the growing-point of a bud or the part of a cone which bears the seeds. The small flakes into which the other [bark] of a tree divides. Scurfy—Covered with small bran-like [scales]. Serrate—Having sharp teeth on margin. Sessile—Seated; without a stalk. Sheath—A tubular envelope or covering such as surround the base of pine-needles. Silky—Covered with long, soft, straight, fine hairs. Simple—Consisting of one part, not [compound]. Sinus—The cleft or opening between two lobes. Sinuate—Wavy. Softwood—A general term given [conifers], the wood of which may or may not be of low density. Stamen—Male organ of flower. Consists of a pollen-bearing [anther] on a filament. Stipule—A leaf-appendage at the base of the leaf-stalk. Stipule-scar—The scar left by the fall of the [stipule]. Stolon—A runner or [basal] branch that may root. Striate—Marked with fine [elongated] ridges or lines. Striations—Long narrow lines or ridges. Strobile—A fruit marked by overlapping scales as in the pine, birches, etc. Sucker—A shoot arising from an underground bud. Superposed—Said of buds when they are arranged one above the other. Symmetrical—Regular as to the number of parts. Having the same number of parts in each circle.
T Terminal—Located at the outer end. Thorn—A stiff, woody, sharp-pointed projection as found on locust; a spine. Tolerant—Applied to trees which endure certain factors, particularly shade. Tomentose—Densely [pubescent]; hairy. Covered with matted-hairs. Tomentum—A dense layer of woolly hairs. Truncate—Ending abruptly, as if cut off at the end. Tufted—Growing in clusters.