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Glossary of leaf morphology

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Chart illustrating leaf morphology terms

The following terms are used to describeleafmorphologyin the description andtaxonomyof plants. Leaves may be simple (a single leaf blade or lamina) or compound (with severalleaflets). 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 theleafarticle.

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,carpelsorscales.Some of these terms are also used for similar-looking anatomical features on animals.

Leaf structure

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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 severalleaflets.Inflowering plants,as well as the blade of the leaf, there may be apetioleandstipules;compound leaves may have arachissupporting the leaflets. Leaf structure is described by several terms that include:[citation needed]

Bipinnate leaf anatomy with labels showing alternative usages
A ternate compound leaf with apetiolebut norachis(or rachillae)
Image Term Latin Description
bifoliolate Having two leaflets[1]
geminate
jugate
bigeminate Having two leaflets, each leaflet being bifoliolate
bipinnate bipinnatus The leaflets are themselvespinnately-compound; twice pinnate
biternate With three components, each with three leaflets
imparipinnate With anodd numberof leaflets, pinnate with a terminal leaflet (the opposite ofparipinnate)
odd-pinnate
paripinnate Pinnate with aneven numberof leaflets, lacking a terminal leaflet (the opposite ofimparipinnate)
even-pinnate
palmately compound palmatus Consisting of leaflets all radiating from one point
pinnately compound pinnatus Having two rows of leaflets on opposite sides of a central axis, seeimparipinnateandparipinnate
simple Leaf blade in one continuous section, without leaflets (not compound)
ternate ternatus With three leaflets
trifoliate trifoliatus
trifoliolate trifoliolatus
tripinnate tripinnatus Pinnately compound in which each leaflet is itself bipinnate

Leaf and leaflet shapes

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Being one of the more visible features, leaf shape is commonly used for plant identification. Similar terms are used for other plant parts, such aspetals,tepals,andbracts.

Oddly pinnate, pinnatifid leaves (Coriandrum sativum,corianderor cilantro)
Partialchlorosisrevealing palmatevenationin simple leaves ofHibiscus mutabilis
Image Term Latin Refers principally to Description
acicular acicularis whole leaf Slender and pointed, needle-like
acuminate acuminatus leaf tip Tapering to a long point in a concave manner
acute leaf tip or base Pointed, having a short sharp apex angled less than 90°
apiculate apiculatus leaf tip Tapering and ending in a short, slender point
aristate aristatus leaf tip Ending in a stiff, bristle-like point
asymmetrical whole leaf With the blade shape different on each side of the midrib
attenuate attenuatus leaf base Having leaf tissue taper down the petiole to a narrow base and always having some leaf material on each side of the petiole
auriculate auriculatus leaf base Having ear-shaped appendages reaching beyond the attachment to the petiole or stem (in case of a seated leaf)
caudate caudatus leaf tip Tailed at the apex
cirrus,cirrate leaf tip Having arachisthat extends beyond the leaf blade or leaflets into a long whip-like extension or cirrus (common in climbing palms); antonym:ecirrate
cordate,cordiform cordatus whole leaf or base Heart-shaped, with the petiole or stem attached to the notch
cuneate cuneatus leaf base Triangular, wedge-shaped, stem attaches to point
cuneiform whole leaf Narrowly triangular, widest on the opposite end from the stem, with the corners at that end rounded
cuspidate cuspidatus leaf tip With a sharp, elongated, rigid tip; tipped with a cusp
deltoid,deltate deltoideus whole leaf Shaped like the Greek letterdelta;triangular with stem attached to side
digitate digitatus whole leaf A palmately compound leaf with leaflets, similar topalmate[2]
ecirrate leaf tip Without acirrus;antonym:cirrate
elliptic ellipticus whole leaf Shaped like anellipse(widest at mid-blade and with similar convex tapering towards apex and base), with a short or no point
emarginate emarginatus leaf tip Slightly indented at the tip
ensiform ensiformis whole leaf Shaped like a sword; long and narrow with a sharp pointed tip
falcate falcatus whole leaf Sickle-shaped
fenestrate fenestratus leaf surface features Large openings through the leaf; seeperforate;sometimes used to describe leafepidermal windows
filiform filiformis whole leaf Thread- or filament-shaped
flabellate flabellatus whole leaf Semi-circular or fan-like
hastate hastatus whole leaf or base Spear-shaped: pointed, with barbs, shaped like a spear point, with flaring pointed lobes at the base
laciniate lacinatus whole leaf Very deeply lobed with the lobes being very drawn out and often making the leaf look somewhat like a branch or a pitchfork
laminar 3-D shape Flat (like most leaves)
lanceolate lanceolatus whole leaf Long, wider in the middle, shaped like alancetip
linear linearis whole leaf Long and very narrow like a blade of grass
lobed lobatus whole leaf Being divided by clefts; may bepinnately lobedorpalmately lobed
lorate loratus whole leaf Having the form of a thong or strap
lyrate lyratus whole leaf Shaped like alyre,pinnately lobedleaf with an enlarged terminal lobe and smaller lateral lobes.See alsoList of lyrate plants.
mucronate mucronatus leaf tip Ending abruptly in a small sharp point as a continuation of the midrib[3]
multifid multi+findere whole leaf Cleft into many parts or lobes
obcordate obcordatus whole leaf Heart-shaped, stem attaches at the tapering end
oblanceolate oblanceolatus whole leaf Much longer than wide and with the widest portion near the tip; reversed lanceolate
oblique leaf base Asymmetrical leaf base, with one side lower than the other
oblong oblongus whole leaf Having an elongated form with slightly parallel sides; roughly rectangular
obovate obovatus whole leaf Teardrop-shaped, stem attaches to the tapering end; reversed ovate
obtrullate whole leaf Reversed trullate; the longer sides meet at the base rather than the apex.
obtuse obtusus leaf tip or base Blunt, forming an angle > 90°
orbicular orbicularis whole leaf Circular
ovate ovatus whole leaf Egg-shaped, with a tapering point and the widest portion near the petiole
palmate palmatus whole leaf Palm-shaped, i.e. with lobes or leaflets stemming from the leaf base[4]
palmately lobed palmatus whole leaf Lobes spread radially from a point[5]
palmatifid palma+findere whole leaf Palm-shaped, having lobes with incisions that extend less than halfway toward the petiole
palmatipartite palma+partiri whole leaf Having palmate lobes with incisions that extend over halfway toward the petiole
palmatisect palma+secare whole leaf Having palmate lobes with incisions that extend almost up, but not quite to the petiole.
pandurate panduratus whole leaf Fiddle-shaped; obovate with a constriction near the middle.
pedate pedatus whole leaf Palmate, with cleft lobes[6]
peltate peltatus stem attachment A round leaf where the petiole attaches near the center, e.g. alotusleaf
perfoliate perfoliatus stem attachment With the leaf blade surrounding the stem such that the stem appears to pass through the leaf
perforate perforatus leaf surface features Many holes, orperforations,on leaf surface. Compare withfenestrate.
pinnately lobed pinna+lobus whole leaf Having lobes pinnately arranged on the central axis
pinnatifid pinna+findere whole leaf Having lobes with incisions that extend less than halfway to the midrib
pinnatipartite pinnatus+partiri whole leaf Having lobes with incisions that extend more than halfway to the midrib
pinnatisect pinnatus+sectus whole leaf Having lobes with incisions that extend almost to, or up to, the midrib
plicate plicatus 3-D shape Folded intopleats,usually lengthwise, serving the function of stiffening a large leaf
reniform reniformis whole leaf Shaped like akidney,with an inward curve on one side
retuse leaf tip With a shallow notch in a round apex
rhomboid,rhombic rhomboidalis whole leaf Diamond-shaped
rounded rotundifolius leaf tip or base Circular, no distinct point
semiterete 3-D shape Rounded on one side and flat on the other
sinuate sinuatus 3-D shape Circularly-lobed leaves
sagittate sagittatus whole leaf Arrowhead-shaped with the lower lobes folded, or curled downward
spatulate spathulatus whole leaf Spoon-shaped; having a broad flat end which tapers to the base
spear-shaped hastatus whole leaf Seehastate.
subobtuse subobtusus leaf tip or base Somewhat blunted; neither blunt nor sharp
subulate subulatus leaf tip Awl-shaped with a tapering point
terete 3-D shape 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 variouslichensandsucculents.
trullate whole leaf Shaped like amasonry trowel
truncate truncatus leaf tip or base With a squared-off end
undulate undulatus 3-D shape Wave-like
unifoliate unifoliatus compound leaves With a single leaflet; it is distinct from a simple leaf by the presence of twoabscission layersand often bypetiolulesandstipels.

Edge

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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 becoarsely dentate,having large teeth

orglandular 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
undulate undulatus With a wavy edge, shallower than sinuate
spiny orpungent spiculatus With stiff, sharp points such asthistles

Leaf folding

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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 calledvernation,ptyxisis the folding of an individual leaf in a bud.

Image Term Latin Description
carinateor keeled carinatus With a longitudinal ridge,keel-shaped
conduplicate 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

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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

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References

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  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. ^MucronateArchived2016-03-03 at theWayback Machine,Answers, from Roget's Thesaurus.
  4. ^"palmate (adj. palmately)".GardenWeb Glossary of Botanical Terms.iVillage GardenWeb. 2006. Archived fromthe originalon 13 February 2009.Retrieved19 October2008.
  5. ^Nelson, Randal C. (2009) [2012]."Leaf description glossary".University of Rochester.Archived fromthe originalon 1 August 2020.Retrieved2 November2017.
  6. ^"Pedate leaf".Retrieved24 February2014.
  7. ^Stearn (2004),pp. 439–440.

Bibliography

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Wikimedia Commons has media related toCategory:Leaf margins.
Wikimedia Commons has media related toCategory:Leaf diagrams.
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