labellum: a lip; in Orchidaceae, the distinctive median petal that serves as an alighting platform for pollinating insects; in Zingiberaceae and Costaceae, a (usually showy) structure derived from petaloid staminodes.
laciniate: slashed into narrow, pointed lobes.
lacrymiform: tear-shaped, i.e. more or less ovoid or obovoid.
lacuna: a gap or cavity.
lamella: a thin, plate-like layer; middle lamella, the layer between the walls of two adjacent cells.
lamellose: composed of or arranged in layers or thin plates.
lamina: the blade of a leaf. cf. blade.
lanceolate: of a leaf, about four times as long as it is broad, broadest in the lower half and tapering towards the tip.
latex: a viscous fluid exuded from the cut surfaces of the leaves and stems of certain plants.
latiseptate: with broad partitions. cf. angustiseptate.
latrorse: turned sideways, i.e. not towards or away from axis; of anthers, opening laterally, i.e. towards adjacent anthers.
leaflet: one of the ultimate segments of a compound leaf.
lectotype: a specimen or illustration selected from among those cited with the original description to serve in place of a holotype where the holotype is missing or destroyed, or where no holotype was designated; isolectotype: a duplicate of the lectotype. cf. type.
legume: a fruit characteristic of the families Mimosaceae, Caesalpiniaceae and Fabaceae, formed from one carpel and either dehiscent along both sides, or indehiscent; in particular, such a fruit that is grown as an edible crop; a crop species in the family Fabaceae.
lemma: in a grass floret, the lower of two bracts enclosing a flower.
lenticel: a loosely-packed mass of cells in the bark of a woody plant, visible on the surface of a stem as a raised powdery spot, through which gaseous exchange occurs.
lenticular: shaped like a biconvex lens.
lepidote: covered with small, membranous scales.
leptosporangiate: of ferns, having sporangia with walls only one cell thick. cf. eusporangiate.
liane: a climbing or twining plant (usually applied to woody climbers).
lignified: woody, due to the deposition of lignin in cell walls.
lignotuber: a woody swelling at the base of the shoot system below or just above the ground, containing adventitious buds from which new shoots develop if the top of the plant is cut off or burnt (common in the shrubby eucalypts ('mallee') and in many other fire-tolerant Australian shrubs).
ligulate: bearing a ligule; strap-shaped.
ligule: a strap-shaped structure; a membranous or hairy appendage on the adaxial surface of a leaf, especially in grasses, at the junction between sheath and blade; a small adaxial appendage near the leaf base in some pteridophytes; the corolla limb in ray flowers of Asteraceae.
limb: the upper, free, spreading portion of a corolla or perianth that is connate at the base; the expanded portion of a sepal or petal above the claw. cf. blade, claw.
linear: very narrow in relation to the length, and with the sides parallel. cf. lorate.
lithophyte: a plant that grows on the surface of unweathered rock.
lobulate: having small or indistinct lobes.
loculicidal: of the dehiscence of a fruit, along lines coinciding with the centres of loculi. cf. septicidal.
loculus (= locule): an enclosed compartment within an organ, e.g. an ovary, an anther. pl. loculi.
lodicule: one of a pair of tiny scales in a grass floret, between the lemma and the fertile parts of the flower, which may be reduced perianth segments.
lomentum: a legume having distinct constrictions or lines of abscission between the seeds and breaking into one-seeded segments when mature.
lorate: of leaves, strap-shaped (moderately long with the two margins parallel). cf. linear.
lumen: the cavity of a plant cell.
lyrate: deeply lobed, with a large terminal lobe and smaller lateral ones.
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Last updated on 13 May 1999.