Bonsai Definitions:

TREE TERMS

Broadleaf -

Any tree that has wide leaves, rather than slim, needle-like leaves as found in conifers. Most broad-leaved trees are deciduous, such as birch, elm, oak, and maple, but some such as arbutus and live oak are evergreen. Also known as hardwoods, though there is an enormous variation in actual wood hardness.

Conifer -

Cone-bearing. Typical examples of conifers include cedars, Douglas-firs, cypresses, firs, junipers, kauris, larches, pines, hemlocks, redwoods, spruces, and yews. Taiga, also known as the boreal forest, is the world's largest land biome characterized by coniferous forests and makes up 29% of the world's forest cover. Immense conifer forests of the world represent the largest terrestrial carbon sink. The wood of conifers is known as softwood. (Mnemonic: conifer = cone)

Deciduous -

"Falling off at maturity" or "tending to fall off", and is typically used in reference to trees or shrubs that lose their leaves seasonally, and to the shedding of other plant structures such as petals after flowering or fruit when ripe. In a more specific sense, deciduous means the dropping of a part that is no longer needed, or falling away after its purpose is finished. In plants it is the result of natural processes. Trees include Maple, many Oaks, Elm, Aspen, and Birch, among others, as well as a number of coniferous genera, such as Larch and Metasequoia. (Wikipedia link.) (Mnemonic: deciduous = dropping)

Palmate -

Leave stem pattern name used in identification. A leaf having several lobes (typically 5–7) whose midribs all radiate from one point. A leaf resembling an open hand, like a palm. (Mnemonic: palmate = palm)

Pinnate -

Leave stem pattern name used in identification. Resembling a feather; having parts or branches arranged on each side of a common axis.

TREE PHYSIOLOGY

Cambium -

The vascular cambium is the source of both the secondary xylem (inwards, towards the pith) and the secondary phloem (outwards), and is located between these tissues in the stem and root. (Wikipedia pix.) (I think of this as kind of the mind of the tree. It expands outwards and is stem-cell-like insofar as turning into xylem (bringing water up) (and then the xylem becomes the heartwood or structure), phloem (bringing energy down from the leaves) (and then phloem becomes outer bark) and even, I think, buds, and roots, etc.)

Desiccation -

Literally the physical removal of water. In bonsai we're generally using the word in a neutral or positive way referring to evaporation of water from the plant leaves - which is part of the process of drawing water up the trunk and branches. On the other hand, if moisture lost through transpiration can't be replaced via uptake by the roots the result is desiccation of the plant itself, negative, meaning drying out. In winter months when the photosynthetic processes are slowed evergreens can continue to lose water at a higher rate than deciduous trees, through their needles. Winter wind accompanying dry periods can accelerate water loss from the needles, and needle death is more extensive on the side of the tree facing the prevailing wind. Other common terms for this type of injury are winter burn, winter drying or winter scorch. (Link Props.)

Lignify -

To become wood. To develop woody tissue as a result of incrustation of lignin during secondary growth.

Mycorrhiza -

Symbiotic association between a fungus and the roots. In a mycorrhizal association, the fungus colonizes the host plant's roots. An important component of soil life and soil chemistry! (Some books suggest gathering and using fallen pine needles when potting so as to introduce these fungi and encourage root growth.) (Wikipedia link.)

Phloem -

Living tissue layer that carries organic nutrients (glucose) to all parts of the plant. In trees, the phloem is the innermost layer of the bark. (Wikipedia pix.)

Xylem -

Long tracheary elements that transport water (also transports some nutrients through the plant). Primary xylem is the xylem that is formed during primary growth from procambium. Secondary xylem is the xylem that is formed during secondary growth from vascular cambium. (Wikipedia pix.)

BONSAI TERMS

Jitta -

Redwood slab / burl for accent plant

Penjing -

Ancient Chinese art of growing trees and plants, kept small by skilled pruning and formed to create an aesthetic shape and the complex illusion of age. Generally fall into one of three categories classified by subject matter: Tree Penjing, Landscape Penjing, and Water and Land Penjing. (Wikipedia link.)

Yamadori -

Naturally dwarfed trees collected from the mountains.