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 structureEdit

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:[citation needed]

 
Bipinnate leaf anatomy with labels showing alternative usages
 
A ternate compound leaf with a petiole but no rachis (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 themselves pinnately-compound; twice pinnate
  biternate With three components, each with three leaflets
  imparipinnate With an odd number of leaflets, pinnate with a terminal leaflet (the opposite of paripinnate)
odd-pinnate
  paripinnate Pinnate with an even number of leaflets, lacking a terminal leaflet (the opposite of imparipinnate)
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, see imparipinnate and paripinnate
  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 shapesEdit

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
  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 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, 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 letter delta; triangular with stem attached to side
  digitate digitatus whole leaf With finger-like lobes, similar to palmate[2]
ecirrate leaf tip Without a cirrus; antonym: cirrate
  elliptic ellipticus whole leaf Shaped like an ellipse, 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; see perforate; sometimes used to describe leaf epidermal 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 a lance tip
  linear linearis whole leaf Long and very narrow like a blade of grass
  lobed lobatus whole leaf Being divided by clefts; may be pinnately lobed or palmately lobed
  lorate loratus whole leaf Having the form of a thong or strap
  lyrate lyratus whole leaf Shaped like a lyre, pinnately lobed leaf with an enlarged terminal lobe and smaller lateral lobes. See also List 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 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. a lotus leaf
  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, or perforations, on leaf surface. Compare with fenestrate.
  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 into pleats, usually lengthwise, serving the function of stiffening a large leaf
  reniform reniformis whole leaf Shaped like a kidney, 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 See hastate.
  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 Circular in cross-section; more or less cylindrical without grooves or ridges
  trullate whole leaf Shaped like a masonry 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 two abscission layers and often by petiolules and stipels.

EdgeEdit

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
  undulate undulatus With a wavy edge, shallower than sinuate
  spiny or pungent spiculatus With stiff, sharp points such as thistles

Leaf foldingEdit

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 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 descriptionsEdit

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 alsoEdit

ReferencesEdit

  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. ^ Also used to describe compound leaves with finger-like leaflets
  3. ^ Mucronate, 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.

BibliographyEdit

External linksEdit