Gymnosperms

Cycad morphology

Cycadophyta
All living cycads are slow-growing, long-lived, dioecious, pachycaul, woody perennials. The stems have a broad, starch-rich cortex, and may be subterranean or aerial in different species. Leaf vasculature traces in the stems are girdling (i.e. traces arise from the stele at a point opposite the point of leaf attachment and encircle the stem). Axillary buds are absent, and any branching occurring is either dichotomous (by equal division of the growing apex) or adventitious (arising from undifferentiated cortical tissues). Leaves are spirally arranged in crowns on the stem apex, pinnate (bipinnate in Bowenia), and lacking stipules (stipules or stipular hoods are present in some genera not occurring in Australia). Leaves are pubescent when young. Leaves are interspersed with reduced scale-leaves, known as cataphylls (except in Stangeriaceae).

Cycadaceae
Habit: dioecious palm like shrubs with aerial or subterranean, pachycaul, cylindrical stems.

Leaves: pinnate, spirally arranged, produced in seasonal growth flushes interspersed with cataphylls, lower leaflets often reduced to spines. Longitudinal ptyxis erect or rarely reflexed, horizontal ptyxis circinate. Leaflets with a single thick midrib and no lateral veins; stomata confined to abaxial surface in most species; individual ptyxis involute. Leaves pubescent, at least when young, with branched or simple transparent trichomes.

Cycad taxonomy
Leaf details for cycas: Leaflet margins entire, lateral veins absent
Leaflet margins irregular or toothed, lateral veins present

Araucaria morphology

Gymnosperm Database
A narrowly conical tree to 60 meters tall. Trunk clear, then later with numerous short shoots. Bark gray, papery, exfoliating in thin strips. Branchlets cord-like, growing in one plane. Leaves awl-like, imbricate, triangular, midrib faint, apex incurved. Male cone oblong-cylindrical, about seven centimeters long by about a centimeter wide; scales triangular, finely teethed, pollen sacs; microsporophylls cuspidate. Female cone about 12 centimeters long by 12 centimeters wide, somewhat spherical (ball-like) with short bracts. Seeds three centimeters long, nut ovate, wings broadly rounded. - Taken from: Silba, J. 1986. An international census of the Coniferae. Phytologia memoir no. 8. Corvallis, Or.: H.N. Moldenke and A.L. Moldenke via the gymnosperm database.

Terminology

• apex: the top or tip of a structure.
• awl-shaped: tapering upward from the base to a slender or rigid point.
• bipinnate: of leaves, twice pinnately divided. cf. pinnate, tripinnate.
• bract: in this case a highly modified leaf
• cortex: the interior region of a stem or root surrounding the vascular cylinder but inside the epidermis (outer skin).
• cusp: a short, abrupt, rigid point.
• cuspidate: tipped with a cusp or sharp and rigid point.
• dioecious: having the male and female reproductive structures on separate plants; unisexual, with male and female flowers on separate plants. cf. monoecious.
• exfoliating: Cleaving off in thin layers.
• imbricate: overlapping, either vertically or spirally, where the lower piece covers the base of the next higher; closely overlapping each other like the tiles of a roof.
• midrib: the central or main rib of a leaf.
• microsporophyll: the leaf bearing the microsporangi.
• monoecious: having the male and female reproductive structures in separate flowers but on the same plant. cf. dioecious.
• pachycaul: thick-stemmed, not `twiggy' (unbranched, or the branches few and thick).
• petiole: the stalk portion of a leaf.
• pinna: a primary segment of the blade of a compound leaf.
• pinnate: divided into pinnae; once-compound. cf. bipinnate, tripinnate.
• stipule: one of a pair of appendages at the bases of leaves in many dicotyledons.

Sources and references

B and T Botanical glossary
Gardenweb Glossary
Excellent photos of Araucariaceae with an image of an Araucaria columnaris female cone