The following terms are used to describe leafmorphology in the description and taxonomy of plants. Leaves may be simple (that is, the leaf blade or 'lamina' is undivided) or compound (that is, the leaf blade is divided into two or more leaflets).[1] The edge of the leaf may be regular or irregular, and may be smooth or have hair, bristles, or spines. For more terms describing other aspects of leaves besides their overall morphology, see the leaf article.
The terms listed here all are supported by technical and professional usage, but they cannot be represented as mandatory or undebatable; readers must use their judgement. Authors often use terms arbitrarily, or coin them to taste, possibly in ignorance of established terms, and it is not always clear whether because of ignorance, or personal preference, or because usages change with time or context, or because of variation between specimens, even specimens from the same plant.[citation needed] For example, whether to call leaves on the same tree "acuminate", "lanceolate", or "linear" could depend on individual judgement, or which part of the tree one collected them from. The same cautions might apply to "caudate", "cuspidate", and "mucronate", or to "crenate", "dentate", and "serrate".
Another problem is to establish definitions that meet all cases or satisfy all authorities and readers. For example, it seems altogether reasonable to define a mucro as "a small sharp point as a continuation of the midrib", but it may not be clear how small is small enough, how sharp is sharp enough, how hard the point must be, and what to call the point when one cannot tell whether the leaf has a midrib at all. Various authors or field workers might come to incompatible conclusions, or might try to compromise by qualifying terms so vaguely that a description of a particular plant practically loses its value.
Use of these terms is not restricted to leaves, but may be applied to morphology of other parts of plants, e.g. bracts, bracteoles, stipules, sepals, petals, carpels or scales. Some of these terms are also used for similar-looking anatomical features on animals.
Leaf structure
Leaves of most plants include a flat structure called the blade or lamina supported by a network of veins, a petiole and a leaf base;[1] but not all leaves are flat, some are cylindrical.[citation needed] Leaves may be simple, with a single leaf blade, or compound, with several leaflets. Compound leaves may be pinnate with pinnae (leaflets) on both sides of a rachis (axis), or may be palmate with multiple leaflets arising from a single point.[1] Leaf structure is described by several terms that include:
Bipinnate leaf anatomy with labels showing alternative usagesA ternate compound leaf with a petiole but no rachis (or rachillae)
Pinnately compound in which each leaflet is itself bipinnate[1]
Leaf and leaflet shapes
Being one of the more visible features, leaf shape is commonly used for plant identification. Similar terms are used for other plant parts, such as petals, tepals, and bracts.
Cylindrical with a circular or distorted circular cross-section and a single surface wrapping around it with no grooves or ridges. Subterete means the leaves are not completely terete, as seen in various lichens and succulents.
Leaf margins (edges) are frequently used in visual plant identification because they are usually consistent within a species or group of species, and are an easy characteristic to observe. Edge and margin are interchangeable in the sense that they both refer to the outside perimeter of a leaf.
Image
Term
Latin
Description
entire
Forma integra
Even; with a smooth margin; without toothing
ciliate
ciliatus
Fringed with hairs
crenate
crenatus
Wavy-toothed; dentate with rounded teeth
crenulate
crenulatus
Finely crenate
crisped
crispus
Curly
dentate
dentatus
Toothed;
may be coarsely dentate, having large teeth
or glandular dentate, having teeth which bear glands
denticulate
denticulatus
Finely toothed
doubly serrate
duplicato-dentatus
Each tooth bearing smaller teeth
serrate
serratus
Saw-toothed; with asymmetrical teeth pointing forward
serrulate
serrulatus
Finely serrate
sinuate
sinuosus
With deep, wave-like indentations; coarsely crenate
lobate
lobatus
Indented, with the indentations not reaching the center
Leaves may also be folded, sculpted or rolled in various ways. If the leaves are initially folded in the bud, but later unrolls it is called vernation, ptyxis is the folding of an individual leaf in a bud.
Folded upwards, with the surfaces close to parallel
cucullate
Forming a hood, margins and tip curved downward
involute
Rolled upwards (towards the adaxial surface)
plicate
plicatus
With parallel folds
reduplicate
Folded downwards, with the surfaces close to parallel
revolute
Rolled downwards (towards the abaxial surface)
supervolute
Opposing left and right halves of lamina folded along longitudinal axis, with one half rolled completely within the other
Latin descriptions
The Latin word for 'leaf', folium, is neuter. In descriptions of a single leaf, the neuter singular ending of the adjective is used, e.g. folium lanceolatum 'lanceolate leaf', folium lineare 'linear leaf'. In descriptions of multiple leaves, the neuter plural is used, e.g. folia linearia 'linear leaves'. Descriptions commonly refer to the plant using the ablative singular or plural, e.g. foliis ovatis 'with ovate leaves'.[8]
↑"palmate (adj. palmately)". GardenWeb Glossary of Botanical Terms. iVillage GardenWeb. 2006. Archived from the original on 13 February 2009. Retrieved 19 October 2008.
↑Nicholson, George; Garret, John; Trail, JWH (1887–1889). The Illustrated Dictionary of Gardening. London: L. Upcott Gill. ISBN978-1436572316.{{cite book}}: ISBN / Date incompatibility (help)
Massey, Jimmy R.; Murphy, James C. (1996). "Vascular plant systematics". NC Botnet. University of North Carolina at Chapel Hill. Retrieved 19 January 2016.
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