Michigan Trees Part 48

[Footnote C: Although formerly cla.s.sed under PINACEAE, recent investigations show it to be the type of a distinct family.]

[Footnote D: It is not intended that this key shall serve as a means of identification of any species of _Salix_ found in Michigan, but it has added simply to give a ready comparison of the four species which are described.]

[Footnote E: It is difficult to distinguish between these species in the absence of summer characters. If leaves can be found on or beneath a tree which is sufficiently segregated from similar trees as to avoid any chance for error, the summer key on the opposite page may be used.]

[Footnote F: A discussion has recently arisen as to whether _Betula lenta_ actually exists in the state, some botanists preferring the name _B. alleghanensis Britt._ for the tree we have so long called Black Birch. Pending further investigation the authors have thought best to retain the old name.

Ref.--Britton: North American Trees, pp. 257-8.]

[Footnote G: [1] means that the acorns mature in the autumn of the first season, hence mature acorns will not be found on the tree, but on the ground beneath the tree.

[2] means that the acorns mature in the autumn of the second season, hence immature acorns will be found on the last season's twigs, and mature acorns on the ground beneath the tree.]

+GLOSSARY+

_With page references to explanatory figures._

_Abortion._ Imperfect development or non-development of an organ or part.

_Ac.u.minate._ Gradually tapering to the apex. Page XII.

_Acute._ Terminating with a sharp angle. Page XII.

_Alternate._ Said of leaves, branches, buds, etc., scattered singly along the stem; not opposite.

_Androgynous._ Composed of both staminate and pistillate flowers.

_Anterior._ The front side of a flower, remote from the axis of inflorescence.

_Anther._ The part of a stamen which bears the pollen. Page xiii.

_Apetalous._ Without petals.

_Apex._ The top, as the tip of a bud or the end of a leaf which is opposite the petiole.

_Apiculate._ Ending in a short-pointed tip.

_Appressed._ Lying close and flat against.

_Aromatic._ Fragrant; with an agreeable odor.

_Axil._ The upper one of the two angles formed by the juncture of a leaf with a stem.

_Axillary._ Situated in an axil.

_Bark._ The outer covering of a trunk or branch.

_Bearded._ Bearing a long, bristle-like appendage, or furnished with long or stiff hairs.

_Berry._ A fruit which is fleshy throughout.

_Bi-pinnate._ Twice pinnate.

_Blade._ The expanded portion of a leaf, etc.

_Bloom._ A powdery or waxy substance easily rubbed off.

_Bract._ A more or less modified leaf subtending a flower or belonging to an inflorescence.

_Branch._ A secondary division of a trunk.

_Branchlet._ A small branch.

_Bud._ An undeveloped stem or branch, with or without scales.

_Bud-scales._ Modified leaves covering a bud.

_Bundle-scars._ Dots on the surface of a leaf-scar, which are scars left by the fibro-vascular bundles which run through the petiole into the blade of the leaf. Page XVI.

_Bur._ A spiny fruit.

_Calyx._ The outer part of a perianth, usually green in color. Page xiii.

_Campanulate._ Bell-shaped.

_Capsule._ A dry fruit of more than one carpel which splits at maturity to release the seeds.

_Carpel._ A simple pistil, or one member of a compound pistil.

_Catkin._ A spike of unis.e.xual flowers, each subtended by a bract, and usually deciduous in one piece.

_Chambered._ Said of pith which is interrupted by hollow s.p.a.ces.

_Ciliate._ Fringed with hairs on the margin.

_Cinereous._ Ash-gray color.

_Claw._ The narrow, stalk-like base of a petal, sepal, etc.

_Cleft._ Cut about half-way to the middle.

_Cl.u.s.ter._ A group of two or more organs (flowers, fruit, etc.) on a plant at a node or end of a stem.