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Section A. Structure and Specialized Characters:
[A. Stem Parts] [B. Stem Types] [C. Stem Structural Types]
1. Twig Surface Parts
- Bud. An immature shoot.
- Internode. A section or region of stem between nodes.
- Leaf Scar. A mark indicating former place of attachment of petiole or leaf base.
- Lenticel. A pore in the bark.
- Node. Region of stem from which a leaf, leaves, or branches arise.
- Prickle. A sharp pointed outgrowth from the epidermis or cortex of any organ.
- Stipular Scar. A mark indicating former place of attachment of stipule.
- Terminal Bud Scale Scar Rings. Several marks in a ring indicating former places of attachment of bud scales.
- Vascular Bundle or Trace Scar. A mark indicating former place of attachment within the leaf scar of the vascular bundle or trace.
2. Major Stem Parts
- Bark. Tissues of plant outside wood or xylem.
- Exfoliating Bark. Bark cracking and splitting off in large sheets.
- Fissured Bark. Split or cracked bark.
- Plated Bark. Split or cracked bark with flat plates between fissures.
- Ringed Bark. Split or cracked bark with circular fissures.
- Shreddy Bark. Soft but coarse fibrous bark, usually shallowly fissured.
- Smooth Bark. Bark without fissures.
- Winged Bark. Bark with one or more thin, flat longitudinal expansions or elongate plates.
- Pith. Centermost tissue of stem, usually soft.
- Chambered Pith. Solid core of pith cells absent, only distinct partitions present.
- Continuous Pith. With solid core of parenchyma or pith cells.
- Diaphragmed Pith. With solid core of pith cells and distinct partitions.
- Hollow Pith. Disintegrated pith with a large central cavity.
- Spongy Pith. Porous, easily compressible pith.
- Wood. Xylem consisting of vessels and/or tracheids, fibers, and parenchyma cells.
- Annual Ring. Usually one year's growth of wood; spring and summer wood.
- Diffuse Porous Wood. Annual rings with vessels or pores more or less evenly distributed.
- Non-porous Wood. Annual rings with tracheids only, no vessels produced in spring or summer wood.
- Ring Porous Wood. Annual rings with vessels or pores usually in the spring wood, in a well defined circular band.
B. Stem Types (Figure 6-2-1)
(Classification based on habit, direction of growth, or position)
- Arborescent. Tree-like in appearance and size.
- Ascending. Inclined upward.
- Cespitose. Short, much-branched, plant forming a cushion.
- Clambering. Sprawling across objects, without climbing structures.
- Climbing. Growing upward by means of tendrils, petioles, or adventitious roots.
- Columnar. Erect with a stout main stem or trunk.
- Decumbent. Reclining or lying on the ground with the tips ascending
- Dichotomous. With equally forked branches or stems.
- Eramous. With unbranched stems.
- Erect. Upright.
- Fastigiate. Strictly erect and parallel.
- Fruticose. Shrubby.
- Geniculate. Abruptly bent at a node, zigzag.
- Procumbent, Prostrate, or Reclining. Trailing or lying flat, not rooting at the nodes; humistrate.
- Ramose. Branched.
- Repent. Creeping or lying flat and rooting at the nodes.
- Soboliferous. With loosely clumped shoots arising some distance apart from rhizomes or under ground suckers.
- Stoloniferous. With runners or propagative shoots rooting at the tip producing new plants; bearing stolons; sarmentose.
- Strict. Stiff and rigid.
- Supine. Prostrate, with parts oriented upward.
- Trailing. Sprawling on ground, usually with adventitious roots.
- Twining. Coiling around an object.
- Virgate. Wand-like; long, slender, and straight.
- Bulb. A short, erect, underground stem surrounded by fleshy leaves.
- Bulbel. A small bulb produced from the base of a larger bulb.
- Bulbil. A small bulb or bulb-like body produced on above ground parts.
- Bulblet. A small bulb, irrespective of origin.
- Caudex. A short, thick, vertical or branched perennial stem usually subterranean, or at ground level.
- Cladode (phylloclad). A flattened main stem resembling a leaf.
- Corm. The enlarged, solid, fleshy base of a stem with scales; an upright underground storage stem.
- Cormel. Small corm produced at base of parent corm.
- Culm. Flowering and fruiting stems of grasses and sedges.
- Pachycauly. Short, thick, frequently succulent stems, as in
- Primocane. The first year non-flowering stem, as in most blackberries; a turion.
- Pterocauly. Winged stems.
- Rhizome. A horizontal underground stem.
- Rootstock. A term applied to miscellaneous types of underground stems or parts.
- Runner or Stolon. An indeterminate, elongate, above ground propagative stem, with long internodes, rooting at the tip forming new plants.
- Sarcocauly. Fleshy stems.
- Scape. A naked flowering stem with or without a few scale leaves, arising from an underground stem.
- Sclerocauly. Hard, dryish stems.
- Spur. A short shoot on which flowers and fruits or leaves are borne.
- Sucker. A shoot arising below ground or from an old stem, usually fast-growing and adventitious; surculose.
- Tendril. Long, slender, coiling branch, adapted for climbing (most tendrils are leaf structures).
- Thorn. A sharp-pointed branch.
- Tiller. A grass shoot produced from the base of the stem.
- Tuber. A thick storage stem, usually not upright.
- Turion. An over-wintering bud, as in Lemna.
- Underground Stolon. A determinate, elongate, underground propagative stem with long internodes forming a bulb or tuber at the tip.
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