Ferns of the Sierra (1960) by Robert J. Rodin

GLOSSARY

Bi-pinnate or bi-pinnately compound — twice pinnate with pinnules scattered along secondary branches (Illustration p. 56).

Cilia — hairs on margins of certain leaves, especially in Selaginella.

Corm — a condensed underground stem which stores food.

Dichotomous — a primitive type of branching which forks repeatedly into two equal branches.

Elliptical — from 3 to 4 times as long as wide, tapering equally from the center toward both ends.

Frond — leaves of certain plants such as ferns and palms (Illustration p. 56).

Imbricated — overlapping of leaves, as shingles on a house.

Indusium — a protective covering over a sorus of a fern (Illustration p. 55).

Lanceolate — lance-shaped, widest near the base, tapering toward the apex.

Linear —a long narrow leaf.

Marginal sori — clusters of sporangia only at the margin of a pinnule.

Oblong — two or three times longer than broad, sides tapering somewhat from the middle, or sides nearly parallel; nearly rectangular.

Obovate — egg-shaped with broadest part away from the attachment.

Obtuse — rounded or blunt.

Orbicular — round or nearly so.

Oval — broadly elliptical, about two times as long as the width.

Ovate — egg-shaped, broadest toward the attachment.

Palmate — branches or leaflets of a leaf all borne at the apex of a common petiole, as all the fingers come from the palm of the hand.

Peltate — round, with a stalk attached on the underside at the middle; shaped like an umbrella.

Petiole — stalk of a leaf or frond.

Pinna (plural: Pinnae) — a primary leaflet of a compound leaf.

Pinnate or pinnately compound — leaflets along both sides of a single petiole or leaf stalk.

Pinnatifid — cleft in a pinnate manner, or deeply pinnately lobed.

Pinnule — the smallest leaflet of a bi-pinnately or more highly compounded leaf.

Rhizome — elongated, horizontal underground stem.

Segment — smallest division of a frond; pinnules.

Seta (plural: Setae) — a soft bristle found at the apex of some leaves.

Sorus (plural: Sori) — a cluster of sporangia on the underside of a fern, usually appearing as a dot or line, (illustration p. 55).

Sporangium (plural: Sporangia) — a reproductive organ producing asexual spores.

Spores — an asexual reproductive structure consisting of a single cell.

Submarginal sorus — a sorus somewhat back from but parallel to the margin of a pinnule.

Tri-pinnate or tri-pinnately compound — a leaf branching three times with pinnules borne on the last branchlets.

[Upside down text:] Did you see a reversal of this curling effect? This optical illusion is more obvious when one realizes that these are not two halves of one nodule but two identical photographs facing opposite directions. Specimen courtesy of Frederick Essig.

[click to enlarge]

Fig. 3 Fossil fern from Mazon Creek, Illinois, that lived during the Coal Age (Carboniferious Period). When a nodule is broken in half, the two halves show an imprint. Note that in one frond the pinnae curl down, in the other they curl up. Now turn this illustration upside down, looking continuously at one fern.