Glossary of Botanical Terms

The study of plants sometimes requires the use of specialized terms to describe unique plant parts or characteristics, thus a glossary of botanical terms used in the species descriptions is included here.

achene: A single-seeded indehiscent fruit derived from a single carpel.

acuminate: Tapering to a sharp point. Usually used when describing the apex of a leaf, petal, and sepal.

amphi-Beringian: Found on both sides of the Bering straight in Alaska and Siberia. See also Browse by Biogeography.

anther: The pollen-releasing organ; where meiosis occurs in the male parts of the flower.

apiculate: Coming into an immediate point. Usually used when describing the apex of a leaf, petal, and sepal.

apomixis: Clonal reproduction via seeds. Ovules are not fertilized, yet develop into viable seeds that are genetically identical to the mother plant.

apothecia: The fruiting body of most lichens. Typically an open cup, disk or button-like structure which releases sexually-produced spores. Apothecia are perennial, not shed after a single season. Singular: apothecium.

auriculate: Having ear shaped appendages (auricles).

awn: A thin, pointed appendage often attached at the tip.

axil: The angle between a leaf and a stem, or a branch and a trunk.

basal rosette: Leaves attached to the base of the plant in a circular arrangement. Plants with basal rosettes often lack stem leaves.

bilateral symmetry: Divisible into mirror-image symmetrical halves along one plane, like a face. Contrast to ‘radial symmetry’.

bipinnate: Leaves 2 times pinnately compound.

bract: A modified leaf (often leaf-like, sometimes scale-like) at the base of a flower or inflorescence; often reduced.

caespitose: Plants that grow in dense tufts or cushions.

calciphile: Plants that like to grow in lime-rich soils.

callus: An outgrowth that is hardened; generally used for the extension of the lemma in grasses.

calyx: The flower whorl that consists of all the sepals, often used when the sepals are fused together.

canaliculate: Grooved or channeled.

capsule: A dry dehiscent fruit that was derived from more than 1 carpel.

carpel: Part of the female reproductive organ, consisting of an ovary, style and stigma. Multiple carpels can be fused.

cauline: Leaves on a stem.

cephalodia: Specialized structures in a lichen for containing cyanobacteria.

ciliate: With hairs along the margin.

circumboreal: Occurring across the boreal belt of the Northern Hemisphere. See also Browse by Biogeography.

circumpolar: Occurring in the arctic around the Northern Hemisphere. See also Browse by Biogeography.

column: The fusion of the staminal filaments into a tube.

compound: A leaf that has been dissected into smaller leaflets.

cordate: Heart shaped.

corolla: The flower whorl that consists of all the petals, often used when the petals are fused together.

cortex: The upper surface of the thallus of a lichen. It is composed of tough fungal cells, unlike the loosely-structured medulla.

corymb: A flat topped cluster of flowers; the lower branches or pedicels have longer stems, leading to the flowers being produced at the same height.

crenate: Rounded toothed margins; generally used to describe leaf margins.

cyanobacteria: A kind of bacteria that can both photosynthesize and fix nitrogen.

cyme: Plant has determinate growth where the apical flower of the inflorescence blooms first.

deciduous: Plants that lose their leaves in fall; not evergreen.

decumbent: Prostrate to the ground but with the tip ascending.

dehiscent: Opening up at maturity; generally referring to fruit or anthers.

deltoid: Triangular.

dioecious: Male and female flowers (or reproductive structures in mosses) born on different plants (i.e. male and female plants); flowers not perfect.

disc floret: Flowers of the Asteraceae family; with a less prominent fused corolla with 5 lobes. In flowers with both ray florets and disk florets, these are in the center of the flowering head.

disjunct: Not connected; in biogeography, populations that are not geographically contiguous.

drupe: Fleshy fruit with a hard stone or pit containing a single seed (like a peach).

elliptic: Widest in the middle, narrower above and below.

entire: Margins containing no serrations, smooth.

fellfield: A slope that due to the snow and wind give these plants characteristic forms; usually references alpine slopes and their respective plants.

filament: Part of the stamen; a ‘stem’ that holds the anther.

flexuose: A plant or part of the plant that curves, bends, or any combination of the two.

foliose: A growth habit that is primarily two-dimensional, like a leaf with a distinguishable top and bottom. Because this growth form has evolved many times, foliose lichens can not be considered a biological group.

follicle: A dry fruit that was derived from a single carpel and splits open from a single side.

fruticose: A growth habit that has a three-dimensional shape, like a bush. Because this growth form has evolved many times, fruticose lichens can not be considered a biological group.

gametophyte: The haploid reproductive stage of plants, generally much smaller than the diploid life cycle (sporophyte). In ferns and clubmosses, this is an independent plant that produces male and female gametes, and fertilization leads to the larger sporophyte. In conifers and flowering plants, the gametophytes are microscopic and contained within the cones or flowers. Fertilization leads to the production of a seed. In bryophytes (mosses, liverworts, and hornworts) this is reversed, with the gametophyte being the largest and most obvious part of the plant appearing at stem and leaf-like structures.

geniculate: An abrupt bending forming a knee at the bend.

glabrous: Without hair.

glandular: Outgrowths that secrete, such as hairs that produce compounds to deter grazing or sticky substances that trap insects.

glaucous: With a waxy residue, usually whitish or bluish in color.

glume: A bract that subtends the spikelet of a grass.

hastate: Shaped like an arrowhead with the bottom lobes facing outwards; compare saggitate.

hygroscopic: Attracting and absorbing water molecules.

indusium: An epidermal outgrowth from the sorus that extends down to cover the sorus, can be peltate (round attached in the center), linear, or reniform (kidney shaped). Plural: indusia.

inflorescence: A part of the plant where the flowers are arranged.

internode: The space on a stem between each node; see node.

involucrum: A whorl of bracts that subtend a flower or inflorescence.

involute: Leaf margins rolling inwards towards the upper side of the leaf.

keel: The length-wise fusion between the lower petals of a flower from the pea family (Fabaceae), forming a shape like the keel of a boat.

laciniate: Irregularly dissected into narrow lobes.

lanceolate: Sword shaped; wider at the base than the tip.

lemma: The lower bract of a grass floret. (See spikelet).

ligulate: Ligule flowers of Asteraceae; strap-shaped with 5 lobes.

ligule: Either: the membranous or hairy appendage at the base of a grass leaf; or, the strap-shaped petals of some flowers in the Asteraceae family.

linear: Thin and elongate with parallel sides.

lobed: Segments that dissect no more than halfway to the midvein or mid section.

lyrate: A leaf that is lobed where the terminal lobe is much larger than the lower lobes.

monoecious: A plant with both male and female flowers on the same plant (imperfect or unisexual flowers) or with flowers have both male and female reproductive parts (perfect or bisexual flowers).

muskeg: Bog dominated by Sphagnum mosses with widely spaced spruce trees; a common habitat type in interior Alaska.

mycorrhizae: The symbiotic relationship between fungal hyphae and plant roots.

nectary: Where nectar is made; usually a gland at the base of a petal or sepal. Also extra-floral nectaries found on leaf bases.

node: Where the stem, leaf, and flower (if any) grow on a stem; the joints of a stem.

nutlet: The fruit type of mints (Lamiaceae) and borages (Boraginaceae). An ovary that breaks into separate pieces.

obcordate: Heart shaped where the attachment is at the narrower end.

oblanceolate: Wider at the tip than at the base with attachment at the narrower end; inverse of lanceolate.

oblong: Much longer that wide with parallel sides.

obovate: Egg shaped with attachment at narrower end.

orbicular: More or less circular in outline.

ovate: Oval or egg shaped with attachment at wider end.

palea: Upper bract surrounding a grass floret. (See spikelet).

palmate: Divided into more than three segments with a central point of attachment, like a hand; usually referring to leaves.

pappus: A structure on the achene in the Asteraceae (sunflower family) that aids in dispersal and consists of bristles or hairs on the achene (the “parachute” on Dandelion seeds is the pappus). Derived from the sepals.

paraphyllia: Tiny, hairlike organs. Singular: paraphyllium.

pedicel: A stem of a flower in an inflorescence.

peduncle: The stem of a solitary flower or an inflorescence.

perfect: Flower contains all floral whorls: sepals, petals, stamens, stigmas.

perianth: The collective term for sepals and petals.

perigynia: A flask-like casing that envelops the fruit of a Carex species. Singular: perigynium.

petiole: The stem of a leaf.

pinnae: The first division of a pinnately compound leaf.

pinnate: A leaf regularly divided into segments with leaflets on either side of the axis, resembling a feather.

pinnatifid: Pinnately lobed.

pistil: The female reproductive organ of a flower, consisting of one or more fused carpels each with a stigma, style, and ovary. Develops into a fruit and contains ovules, which can become seeds if fertilized.

pistillate: Flowers imperfect, containing only female reproductive parts. Female flowers.

pubescence: Small hairs that are irregularly arranged and sparse.

pycnidia: Specialized structures in lichens which asexually produce spores.

raceme: An inflorescence that has unbranched pedicillate flowers.

radial symmetry: Divisible into symmetric halves along multiple planes, such as in a starfish or a rose flower. In contrast to ‘bilateral symmetry’.

ray floret: Flowers of the Asteraceae with prominent strap-shaped petals. In flowers with ray and disk florets, these make up the outer margin of the flowering head. In some species, all florets are ray florets.

receptacle: The fleshy part of the pedicel the flower is attached to.

reniform: Kidney shaped.

retuse: A shallow notch at the apex.

revolute: Leaf margins rolled in towards the underside.

rhizomatous: Spreading by rhizomes (underground stems).

rhizoid: A root-like structure which anchors a moss and absorbs nutrients. Not true roots, as they lack vascular tissue.

rhizome: Underground stem.

root nodules: Areas on roots of certain plants that house cyanobacteria to fix nitrogen.

saggitate: Shaped like an arrowhead with the bottom lobes facing downwards; compare hastate.

scape: A long peduncle without leaves, usually arising from a basal rosette.

scarious: Thin and dry in texture, generally not green.

semi-serotinous: Plants that will open fruit or cones to disperse seeds due to heat but does not need heat exclusively to open fruit or cones.

sepal: The outer most whorl of a flower, often leaf-like and initially protecting the flower bud.

serotinous: A condition of seed dispersal in some plants needing heat (generally produced by wildfire) to allow opening of fruit or cones to disperse seeds.

serrate: tooth like projections along the margin; usually in reference to leaves.

sessile : Without a stalk, directly attached.

silique: Fruit type of the mustard family (Brassicaceae), where the capsule is longer than wide, dehisces from two valves and has a persistent middle septum.

simple: Not compound; a leaf that has not been divided into many leaflets.

sorus: A cluster of sporangia on a fern leaf. Plural: sori.

spatulate: Spatula shaped; round at the tip and tapering towards the base.

spike: All flowers sessile to a single stem.

spikelet: A cluster of grass flowers. The two outermost bracts are called glumes, and each flower inside has two more bracts, the lemma (lower) and palea (upper).

sporangia: A case or sac that houses spores.

spore: A single-celled reproductive unit which can give rise to a new individual.

sporophore: The part of the leaves in the genus Botrychium that holds the sporangia; the fertile leaf.

sporophyte: The diploid part of the plant life cycle consisting of the stems, leaves, and flowers (if any). In bryophytes (mosses, liverworts, and hornworts) the sporophyte stage presents as a capsule on a specialized stalk called a seta.

stamen: The male reproductive organ, consisting of a filament (stalk-like appendage) and anther, which releases pollen.

staminate: Imperfect flowers that contain only stamens; male flowers.

stellate: Hairs that arise from a single base; looks star-shaped.

stigma: The receptive part of an ovary, which serves to catch pollen, often sticky.

stipe: The ‘stem’ of a fern leaf.

stolon: An aboveground stem that roots and buds into another individual; runners, as in strawberry plants.

stoloniferous: Spreading by stolons (aboveground stems).

strobilus: A spore-producing cone as in the clubmosses (Lycopodiaceae), but can also reference conifer cones as well. Plural: strobilii.

style: The stalk of the ovary that holds up the stigma.

subtend: To be attached below.

tepal: Term used for petals and sepals that are not easily discernable from one another.

terete: Round in cross section.

ternate: In orders of three.

thallus: The body of the lichen, containing both algae and fungi. This is the vegetative part of the lichen. Plural: thalli.

tomentose: Short hairs that are densely packed together.

tomentum: A felted covering of rhizoids that appears wooly.

toothed: Leaf margin with saw-like indentations.

trifoliate: Leaf divided into three leaflets.

trophophore: The sterile part of the leaf of the genus Botrychium, which is green and photosynthetic.

tussock: Dense hummock formed by certain grass or sedge species.

usnic acid: A secondary chemical found in many lichens, giving them a characteristic yellowish cast. Usnic acid in lichens is thought to act as a sunscreen and as chemical defense against grazing.

viviparous: Producing bulbs that begin to develop before becoming detached from the ‘mother’ plant, often in the place of flowers.

whorled: Having more than 3 leaves per node.