PEI Museum and Heritage Foundation AC CDC Nature PEI

Illustrated Flora of Prince Edward Island


See also Harris and Harris (1994).

Abaxial – the lower surface, or the surface away from the axis. Compare adaxial
Acroscopic – oriented towards the terminal end. Compare basiscopic
Actinomorphic – radially symmetrical – lines drawn down any plane will produce mirror images on either side. Compare zygomorphic
Acuminate – gradually tapering to a sharp point, the sides becoming concave. Comparer mucronate
Acute – tapering to a pointed apex, the sides remaining straight and forming an angle less than 90 degrees. Compare obtuse
Adaxial – the upper surface, or the surface closest to the axis. Compare abaxial
Alternate – arranged alternately, e.g. with a single leaf present per stem node. Compare opposite, whorled
Anther – the expanded, apical portion of the stamen that bears pollen
Anthesis – when a flower is fully expanded and functional, the flowering period
Apical – located at the apex or terminal end
Appressed – oriented close or pressed against another organ
Aril – a fleshy thickening of the seed coat, as in Canada Yew (Taxus canadensis)
Basal – positioned or arising from the base, as in leaves arranged at the base of a stem. Compare cauline
Basiscopic – oriented towards the base. Compare acroscopic
Bilateral – arranged on two sides of an axis
Bipinnate – pinnate twice, with initial division pinnately divided once more
Bract – a reduced leaf at the base of a flower or inflorescence; in conifers, bracts arise from the axis of the seed cone
Calyx – the collective name for all sepals of a flower; the outer perianth whorl
Capsule – a dry, dehiscent fruit with more than one carpel
Carpel – a simple pistil, or one component of a compound pistil
Cauline – relating to the stem, as in leaves borne on the stem above the ground. Compare basal
Clavate – club-shaped, gradually widening to a clubbed apex
Conical – cone-shaped, tapering away from point of attachment
Connate – fused, as in the fusion of staminal filaments to form a tube
Cordate – heart-shaped, i.e., with a sinus at the base
Corolla – the collective name for all petals of a flower; the inner perianth whorl
Crenate – rounded teeth. Compare dentate, serrate
Cuneate – tapering in a wedge-shape
Dehiscent – opening at maturity to release contents, as in fruit releasing seeds or anthers releasing pollen
Deltate – shaped like an equilateral triangle
Dentate – toothed, the teeth pointing outward. Compare crenate, serrate
Dimorphic – with two forms
Distal – toward the tip, or the end of an organ opposite its attachment point. Compare proximal
Drupe – a fleshy, indehiscent fruit with a stony inner layer enclosing usually a single seed, as in Cherries (Prunus)
Elliptical – with the shape of an ellipse or narrow oval; broadest at the middle and narrower at the two equal ends
Equitant – overlapping or straddling in two ranks, as in the leaves of Iris
Filament – a thread-like structure, usually referring to the stalk of the stamen, supporting the anther
Fringed – with hairs, bristles, or thin projections along the margins
Frond – the leaf of a fern or palm
Gemma – readily-detaching vegetative propagules, consisting of a ring of six leaves arranged in a cup-like shape, as in the Firmosses (Huperzia).
Glaucous – with a white or bluish waxy coating
Hemipollinarium – half of a pollinarium
Herbaceous – like a herb, i.e., not woody or evergreen
Hirsute –with coarse, stiff, straight hairs
Hyaline – thin, membranous, transparent or translucent
Indehiscent – a type of fruit, not opening at maturity along defined lines or pores
Indusium – in ferns, an epidermal growth from the frond covering the sorus
Inferior – attached beneath, e.g. an ovary attached beneath the receptacle, as in Blueberries (Vaccinium). Compare superior
Inflorescence – the flowering portion of a plant; the arrangement of the flowers on the flowering axis
Internode – portion of a stem between two nodes
Labellum – the highly-modified lip petal in orchid flowers
Lacerate – cut irregularly, as if torn
Lanceolate – lance-shaped, much longer than wide, the widest point below the middle
Lateral – borne on or at the side
Linear – resembling a line; long and narrow with relatively parallel sides
Lobe – a division or segment or an organ such as a leaf
Midvein – the central vein, usually of a leaf
Monomorphic – with one form
Mucronate – tipped with an abrupt, short, sharp point. Compare acuminate
Myco-heterotrophic – deriving energy from fungal associations, usually mycorrhizae, rather than photosynthesis
Node – part of the stem where leaves or branches originate
Oblanceolate – inversely lanceolate, the base narrower than the apex
Oblong – two to four times longer than broad, with nearly parallel sides
Obtuse – tapering or rounding to apex, with the sides forming and angle greater than 90 degrees. Compare acute
Opposite – arranged oppositely, e.g. with two leaves arising per node
Orbicular – roughly circular in outline
Ovary – the expanded basal part of the pistil containing the ovules
Ovate – egg-shaped in outline, broadest below the middle
Ovoid – egg-shaped (applied to three-dimensional features)
Ovule – an immature seed
Panicle – a branched racemose inflorescence. Compare raceme
Pedicel – the stalk of a single flower, or a grass spikelet. Compare peduncle
Peduncle – the stalk of an inflorescence (more than one flower). Compare pedicel
Peltate – shield-shaped, the attachment point on the lower surface rather than an edge
Perianth – the calyx and corolla of a flower
Petal – an individual segment or member of the corolla, usually coloured or white
Petiole – the stalk of a leaf
Petiolule – the stalk of a leaflet (in a compound leaf)
Pinna – the first division of a pinnate fern frond
Pinnate – as in a compound leaf or fern frond, fully divided into leaflets or pinnae along opposite sides of an elongate axis
Pinnatifid – as in a fern frond, pinnately cleft but not completely divided to the midrib or rachis
Pinnule – the pinnate division of a pinna in a bipinnately compound leaf or frond
Pistil – the female component of a flower, usually consisting of an ovary, style and stigma
Pollinarium – in Orchids, the pollen-bearing structure that attaches to pollinators
Proximal – toward the base or the attached end of an organ. Compare distal
Pubescent – hairy
Rachis – the midrib of a fern frond or axis of an inflorescence
Raceme – an unbranched, elongate inflorescence with pedicelled flowers. Compare spike, panicle
Radial – with structures radiating from a central point, as spokes on a wheel
Receptacle – the part of the pedicel where all floral parts are attached
Reduced – (relative) of smaller size
Resupinate – upside-down, due to twisting of the pedicel, as in the flowers of most of our Orchids
Rhizome – a horizontal, underground stem
Scape – a leafless peduncle arising from ground-level, usually from a basal rosette
Scapose – having flowers borne on a scape
Sepal – a segment of the calyx
Serrate – with saw-like teeth, pointed and facing toward the apex. Compare dentate, crenate
Sessile – directly attached, not borne on a stalk
Sheath – the portion of an organ which surrounds, at least partly, another organ, e.g. in grasses, where the bases of leaves form a sheath around the stem
Sheathing – forming a sheath
Sinus – the depression or recess between two lobes or teeth
Sorus – a cluster of sporangia on the surface of a fern frond, usually covered by an indusium
Spadix – a spicate inflorescence with small flowers crowded on a thickened axis, as in Jack-in-the-pulpit (Arisaema triphyllum)
Spathe – a large bract subtending and often enclosing an inflorescence
Spatulate – spatula-shaped, broadest near the apex, gradually tapering to the base
Spike – an unbranched inflorescence with sessile (or subsessile) flowers. Compare raceme
Sporangium – the spore-bearing case in ferns. Usually numerous and arranged in sori
Sporophore – the spore-bearing portion of a frond, as in Ophioglossaceae
Spur – a hollow, elongated, sac-like appendage of the calyx or corolla, as in Platanthera
Stamen – the male component of a flower, consisting of a filament and anther
Stigma – the part of the pistil which is receptive to pollen
Stipule – leaf-like appendages sometimes found at leaf-bearing nodes
Stomate (pl. stomata) – a pore or aperture surrounded by two guard cells, which allows gas exchange
Strobilus – a cone or an inflorescence resembling a cone, as in the Clubmosses (Lycopodiaceae)
Style – the usually narrowed stalk-like portion of the pistil connecting the stigma to the ovary
Superior – attached above, e.g. an ovary attached above the receptacle. Compare inferior
Tepal – a perianth whorl that cannot be defined as either a sepal or petal
Terete – round in cross-section
Terminal – at the tip or apex
Ternate – divided in threes, as in Bracken Fern (Pteridium aquilinum)
Tripinnate – pinnately compound three times
Trophophore – the sterile, photosynthesizing portion of a frond, as in Ophioglossaceae
Umbel – a flat-topped or convex inflorescence with pedicels mostly arising from a common point, like an umbrella
Whorled – arranged in whorls, e.g. with three or more leaves arising from a node
Zygomorphic – bilaterally symmetrical – only one line down the middle can be drawn that will produce mirror images on either side. Compare actinomorphic