Glossary of leaf morphology


The following is a defined list of terms which are used to describe leaf morphology in the description and taxonomy of plants. Leaves may be simple or compound. The edge of the leaf may be regular or irregular, may be smooth or bearing 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. 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.

Leaf structure

Leaves of most plants include a flat structure called the blade or lamina, but not all leaves are flat, some are cylindrical. Leaves may be simple, with a single leaf blade, or compound, with several leaflets. In flowering plants, as well as the blade of the leaf, there may be a petiole and stipules; compound leaves may have a rachis supporting the leaflets. Leaf structure is described by several terms that include:
ImageTermLatinDescription
Having two leaflets
Having two leaflets
Having two leaflets
Having two leaflets, each leaflet being bifoliolate
bipinnatusThe leaflets are themselves pinnately-compound; twice pinnate
With three components, each with three leaflets
With an odd number of leaflets, pinnate with a terminal leaflet
With an odd number of leaflets, pinnate with a terminal leaflet
Pinnate with an even number of leaflets, lacking a terminal leaflet
even-pinnatePinnate with an even number of leaflets, lacking a terminal leaflet
palmatusConsisting of leaflets all radiating from one point
compoundpinnatusHaving two rows of leaflets on opposite sides of a central axis, see [|imparipinnate] and [|paripinnate]
simpleLeaf blade in one continuous section, without leaflets
ternatusWith three leaflets
trifoliatusWith three leaflets
trifoliolatusWith three leaflets
tripinnatusPinnately compound in which each leaflet is itself bipinnate

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.
revealing palmate venation in simple leaves of Hibiscus mutabilis
ImageTermLatinRefers principally toDescription
acicularisentire leafSlender and pointed, needle-like.
acuminatusleaf tipTapering to a long point in a concave manner.
leaf tip or basePointed, having a short sharp apex angled less than 90°.
apiculatusleaf tipTapering and ending in a short, slender point.
aristatusleaf tipEnding in a stiff, bristle-like point.
attenuatusleaf baseHaving leaf tissue taper down the petiole to a narrow base, always having some leaf material on each side of the petiole.
auriculatusleaf baseHaving ear-shaped appendages reaching beyond the attachment to the petiole or to the stem.
entire leafWith the blade shape different on each side of the midrib.
caudatusleaf tipTailed at the apex.
, cordatusentire leafHeart-shaped, with the petiole or stem attached to the notch.
cuneatusleaf baseTriangular, wedge-shaped, stem attaches to point.
cuspidatusleaf tipWith a sharp, elongated, rigid tip; tipped with a cusp.
, deltoideusentire leafShaped like Greek letter Delta, triangular, stem attaches to side.
digitatusentire leafWith finger-like lobes, similar to palmate.
ellipticusentire leafOval, with a short or no point.
ensiformisentire leafShaped like a sword, long and narrow with a sharp pointed tip.
emarginatusleaf tipSlightly indented at the tip.
falcatusentire leafSickle-shaped.
fenestratussurface featuresLarge openings through the leaf, see [|perforate]. Sometimes use to describes leaf epidermal windows.
filiformisentire leafThread- or filament-shaped.
flabellatusentire leafSemi-circular, or fan-like.
hastatusentire leafSpear-shaped: Pointed, with barbs, shaped like a spear point, with flaring pointed lobes at the base.
lacinatusentire leafVery deeply lobed, the lobes being very drawn out, often making the leaf look somewhat like a branch or a pitchfork.
lanceolatusentire leafLong, wider in the middle, shaped like a lance tip.
3-d shapeFlat
linearisentire leafLong and very narrow like a blade of grass.
lobatusentire leafBeing divided by clefts, may be [|pinnately] lobed or palmately lobed.
loratusentire leafHaving the form of a thong or strap.
lyratusentire leafShaped like a lyre, pinnately lobed leaf with an enlarged terminal lobe and smaller lateral lobes.
mucronatusleaf tipEnding abruptly in a small sharp point as a continuation of the midrib.
multi + findereentire leafCleft into many parts or lobes.
obcordatusentire leafHeart-shaped, stem attaches at the tapering end.
oblanceolatusentire leafMuch longer than wide and with the widest portion near the tip, reversed lanceolate.
leaf baseAsymmetrical leaf base, with one side lower than the other
oblongusentire leafHaving an elongated form with slightly parallel sides, roughly rectangular.
obovatusentire leafTeardrop-shaped, stem attaches to the tapering end; reversed ovate.
obtrullateentire leafReversed trullate, the longer sides meet at the base rather than the apex.
obtusustipBlunt, forming an angle > 90°.
orbicularisentire leafCircular.
ovatusentire leafOval, egg-shaped, with a tapering point and the widest portion near the petiole.
palmatusentire leafPalm-shaped, i.e., with lobes or leaflets stemming from the leaf base.
palmatusentire leafLobes spread radially from a point.
palma + findereentire leafPalm-shaped, having lobes with incisions that extend less than half-way toward the petiole.
palma + partirientire leafHaving lobes with incisions that extend over half-way toward the petiole.
palma + secareentire leafHaving lobes with incisions that extend almost up, but not quite to the petiole.
panduratusentire leafFiddle-shaped; obovate with a constriction near the middle.
pedatusentire leafPalmate, with cleft lobes.
peltatusstem attachmentA round leaf where the petiole attaches near the center. An example would be a lotus leaf.
perfoliatusstem attachmentWith the leaf blade surrounding the stem such that the stem appears to pass through the leaf.
perforatusleaf surface featuresMany holes, or perforations on leaf surface. Compare with [|fenestrate].
lobedpinna + lobusentire leafHaving lobes pinnately arranged on the central axis.
pinna + findereentire leafHaving lobes with incisions that extend less than half-way toward the midrib.
pinnatus + partirientire leafHaving lobes with incisions that extend more than half-way toward the midrib.
pinnatus + sectusentire leafHaving lobes with incisions that extend almost, or up to midrib.
plicatus3-d shapeFolded into, usually lengthwise, serving the function of stiffening a large leaf.
reniformisentire leafShaped like a kidney: an oval with an inward curve on one side.
leaf tipWith a shallow notch in a round apex.
, rhomboidalisentire leafDiamond-shaped.
rotundifoliusleaf tip or baseCircular, no distinct point.
semiterete3-d shapeRounded on one side, but flat on the other.
sinuatus3-d shapeCircularly-lobed kind of leaves
sagittatusentire leafArrowhead-shaped with the lower lobes folded, or curled downward
spathulatusentire leafSpoon-shaped; having a broad flat end which tapers to the base
-shapedhastatusentire leafsee [|hastate].
subobtususleaf tip or baseSomewhat blunted, neither blunt nor sharp
subulatusleaf tipAwl-shaped with a tapering point
3-d shapeCircular in cross-section; more or less cylindrical without grooves or ridges.
entire leafShaped like a bricklayer's trowel
truncatusleaf tip or baseWith a squared-off end
undulatus3-d shapeWave-like
unifoliatuscompound leavesWith a single leaflet. It is distinct from a simple leaf by the presence of two abcission layers and often by petiolules and stipels

Edge

Leaf margins 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.
ImageTermLatin adjectiveDescription
Forma
integra		Even; with a smooth margin; without toothing
ciliatusFringed with hairs
crenatusWavy-toothed; dentate with rounded teeth
crenulateFinely crenate
crispuscurly
dentatusToothed. May be coarsely dentate, having large teeth, or glandular dentate, having teeth which bear glands
denticulatusFinely toothed
duplicato-dentatusEach tooth bearing smaller teeth
serratusSaw-toothed; with asymmetrical teeth pointing forward
serrulatusFinely serrate
sinuosusWith deep, wave-like indentations; coarsely crenate
lobatusIndented, with the indentations not reaching the center
lobulatusWith small lobes
undulatusWith a wavy edge, shallower than sinuate
or spiculatusWith stiff, sharp points such as thistles

Leaf folding

Leaves may also be folded or rolled in various ways. If the leaves are initially folded in the bud, but later unrolls it is called vernation, is the folding of an individual leaf in a bud.
ImageTermLatinDescription
or keeledcarinatuswith a longitudinal ridge
folded upwards, with the surfaces close to parallel
forming a hood, margins and tip curved downward
rolled upwards
plicatuswith parallel folds
folded downwards, with the surfaces close to parallel
rolled downwards
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'.