Glossary of leaf morphology

The following terms are used to describe leaf morphology in the description and taxonomy of plants. Leaves may be simple (a single leaf blade or lamina) or compound (with several leaflets). 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.

Chart illustrating leaf morphology terms

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.

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, 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:

Bipinnate leaf anatomy with labels showing alternative usages
A ternate compound leaf with a petiole but no rachis (or rachillae)
Image Term Latin Description
bifoliolateHaving two leaflets[1]
geminate
jugate
bigeminateHaving two leaflets, each leaflet being bifoliolate
bipinnatebipinnatusThe leaflets are themselves pinnately-compound; twice pinnate
biternateWith three components, each with three leaflets
imparipinnateWith an odd number of leaflets, pinnate with a terminal leaflet (the opposite of paripinnate)
odd-pinnate
paripinnatePinnate with an even number of leaflets, lacking a terminal leaflet (the opposite of imparipinnate)
even-pinnate
palmately compoundpalmatusConsisting of leaflets all radiating from one point
pinnately compoundpinnatus Having two rows of leaflets on opposite sides of a central axis, see imparipinnate and paripinnate
simpleLeaf blade in one continuous section, without leaflets (not compound)
ternateternatusWith three leaflets
trifoliate trifoliatus
trifoliolate trifoliolatus
tripinnatetripinnatusPinnately 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.

Oddly pinnate, pinnatifid leaves (Coriandrum sativum, coriander or cilantro)
Partial chlorosis revealing palmate venation in simple leaves of Hibiscus mutabilis
Image Term Latin Refers principally to Description
acicularaciculariswhole leafSlender and pointed, needle-like
acuminateacuminatusleaf tipTapering to a long point in a concave manner
acuteleaf tip or basePointed, having a short sharp apex angled less than 90°
apiculateapiculatusleaf tipTapering and ending in a short, slender point
aristatearistatusleaf tipEnding in a stiff, bristle-like point
asymmetricalwhole leafWith the blade shape different on each side of the midrib
attenuateattenuatus leaf baseHaving leaf tissue taper down the petiole to a narrow base and always having some leaf material on each side of the petiole
auriculateauriculatus leaf baseHaving ear-shaped appendages reaching beyond the attachment to the petiole or stem (in case of a seated leaf)
caudatecaudatusleaf tipTailed at the apex
cirrus, cirrateleaf tipHaving a rachis that extends beyond the leaf blade or leaflets into a long whip-like extension or cirrus (common in climbing palms); antonym: ecirrate
cordate, cordiformcordatuswhole leaf or baseHeart-shaped, with the petiole or stem attached to the notch
cuneatecuneatusleaf baseTriangular, wedge-shaped, stem attaches to point
cuneiformwhole leafNarrowly triangular, widest on the opposite end from the stem, with the corners at that end rounded
cuspidatecuspidatusleaf tipWith a sharp, elongated, rigid tip; tipped with a cusp
deltoid, deltatedeltoideuswhole leafShaped like the Greek letter delta; triangular with stem attached to side
digitatedigitatuswhole leafA palmately compound leaf with leaflets, similar to palmate[2]
ecirrateleaf tipWithout a cirrus; antonym: cirrate
ellipticellipticuswhole leafShaped like an ellipse (widest at mid-blade and with similar convex tapering towards apex and base), with a short or no point
emarginateemarginatus leaf tipSlightly indented at the tip
ensiformensiformiswhole leafShaped like a sword; long and narrow with a sharp pointed tip
falcatefalcatuswhole leafSickle-shaped
fenestratefenestratusleaf surface featuresLarge openings through the leaf; see perforate; sometimes used to describe leaf epidermal windows
filiformfiliformiswhole leafThread- or filament-shaped
flabellateflabellatuswhole leafSemi-circular or fan-like
hastatehastatuswhole leaf or baseSpear-shaped: pointed, with barbs, shaped like a spear point, with flaring pointed lobes at the base
laciniatelacinatus whole leafVery deeply lobed with the lobes being very drawn out and often making the leaf look somewhat like a branch or a pitchfork
laminar3-D shapeFlat (like most leaves)
lanceolatelanceolatuswhole leafLong, wider in the middle, shaped like a lance tip
linearlineariswhole leafLong and very narrow like a blade of grass
lobedlobatuswhole leafBeing divided by clefts; may be pinnately lobed or palmately lobed
lorateloratuswhole leafHaving the form of a thong or strap
lyratelyratuswhole leafShaped like a lyre, pinnately lobed leaf with an enlarged terminal lobe and smaller lateral lobes. See also List of lyrate plants.
mucronatemucronatus leaf tipEnding abruptly in a small sharp point as a continuation of the midrib[3]
multifidmulti + finderewhole leafCleft into many parts or lobes
obcordateobcordatuswhole leafHeart-shaped, stem attaches at the tapering end
oblanceolateoblanceolatuswhole leafMuch longer than wide and with the widest portion near the tip; reversed lanceolate
obliqueleaf baseAsymmetrical leaf base, with one side lower than the other
oblongoblonguswhole leafHaving an elongated form with slightly parallel sides; roughly rectangular
obovateobovatuswhole leafTeardrop-shaped, stem attaches to the tapering end; reversed ovate
obtrullatewhole leafReversed trullate; the longer sides meet at the base rather than the apex.
obtuseobtususleaf tip or baseBlunt, forming an angle > 90°
orbicularorbiculariswhole leafCircular
ovateovatuswhole leafEgg-shaped, with a tapering point and the widest portion near the petiole
palmatepalmatuswhole leafPalm-shaped, i.e. with lobes or leaflets stemming from the leaf base[4]
palmately lobedpalmatuswhole leafLobes spread radially from a point[5]
palmatifidpalma + finderewhole leafPalm-shaped, having lobes with incisions that extend less than halfway toward the petiole
palmatipartitepalma + partiriwhole leafHaving palmate lobes with incisions that extend over halfway toward the petiole
palmatisectpalma + secarewhole leafHaving palmate lobes with incisions that extend almost up, but not quite to the petiole.
panduratepanduratus whole leafFiddle-shaped; obovate with a constriction near the middle.
pedatepedatuswhole leafPalmate, with cleft lobes[6]
peltatepeltatusstem attachmentA round leaf where the petiole attaches near the center, e.g. a lotus leaf
perfoliateperfoliatusstem attachmentWith the leaf blade surrounding the stem such that the stem appears to pass through the leaf
perforateperforatusleaf surface features Many holes, or perforations, on leaf surface. Compare with fenestrate.
pinnately lobedpinna + lobuswhole leafHaving lobes pinnately arranged on the central axis
pinnatifidpinna + finderewhole leafHaving lobes with incisions that extend less than halfway to the midrib
pinnatipartitepinnatus + partiriwhole leafHaving lobes with incisions that extend more than halfway to the midrib
pinnatisectpinnatus + sectuswhole leafHaving lobes with incisions that extend almost to, or up to, the midrib
plicateplicatus3-D shapeFolded into pleats, usually lengthwise, serving the function of stiffening a large leaf
reniformreniformiswhole leafShaped like a kidney, with an inward curve on one side
retuseleaf tipWith a shallow notch in a round apex
rhomboid, rhombicrhomboidaliswhole leafDiamond-shaped
roundedrotundifoliusleaf tip or baseCircular, no distinct point
semiterete3-D shapeRounded on one side and flat on the other
sinuatesinuatus 3-D shapeCircularly-lobed leaves
sagittatesagittatuswhole leafArrowhead-shaped with the lower lobes folded, or curled downward
spatulatespathulatuswhole leafSpoon-shaped; having a broad flat end which tapers to the base
spear-shapedhastatus whole leafSee hastate.
subobtusesubobtususleaf tip or baseSomewhat blunted; neither blunt nor sharp
subulatesubulatusleaf tipAwl-shaped with a tapering point
terete3-D shapeCircular in cross-section; more or less cylindrical without grooves or ridges
trullatewhole leafShaped like a masonry trowel
truncatetruncatusleaf tip or baseWith a squared-off end
undulateundulatus3-D shapeWave-like
unifoliateunifoliatuscompound leavesWith a single leaflet; it is distinct from a simple leaf by the presence of two abscission layers and often by petiolules and stipels.

Edge

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
entireForma
integra
Even; with a smooth margin; without toothing
ciliateciliatusFringed with hairs
crenatecrenatusWavy-toothed; dentate with rounded teeth
crenulatecrenulatusFinely crenate
crispedcrispusCurly
dentatedentatusToothed;

may be coarsely dentate, having large teeth

or glandular dentate, having teeth which bear glands

denticulatedenticulatusFinely toothed
doubly serrateduplicato-dentatusEach tooth bearing smaller teeth
serrateserratusSaw-toothed; with asymmetrical teeth pointing forward
serrulateserrulatusFinely serrate
sinuatesinuosusWith deep, wave-like indentations; coarsely crenate
lobatelobatusIndented, with the indentations not reaching the center
undulateundulatusWith a wavy edge, shallower than sinuate
spiny or pungentspiculatusWith stiff, sharp points such as thistles

Leaf folding

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.

Image Term Latin Description
carinate or keeledcarinatusWith a longitudinal ridge, keel-shaped
conduplicateFolded upwards, with the surfaces close to parallel
cucullateForming a hood, margins and tip curved downward
involuteRolled upwards (towards the adaxial surface)
plicateplicatusWith parallel folds
reduplicateFolded downwards, with the surfaces close to parallel
revoluteRolled downwards (towards the abaxial surface)
supervoluteOpposing 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'.[7]

See also

References

  1. Radford, A.E.; Dickison, W.C.; Massey, J.R.; Bell, C.R. (1976). "Phytography - Morphological Evidence". Vascular Plant Systematics. Harper and Row, New York.
  2. Index of Garden Plants, Mark Griffiths, Timber Press, 1992
  3. Mucronate Archived 2016-03-03 at the Wayback Machine, Answers.com, from Roget's Thesaurus.
  4. "palmate (adj. palmately)". GardenWeb Glossary of Botanical Terms. iVillage GardenWeb. 2006. Archived from the original on 13 February 2009. Retrieved 19 October 2008.
  5. Nelson, Randal C. (2009) [2012]. "Leaf description glossary". University of Rochester. Archived from the original on 1 August 2020. Retrieved 2 November 2017.
  6. "Pedate leaf". Retrieved 24 February 2014.
  7. Stearn (2004), pp. 439–440.

Bibliography

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