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A |
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- acuminate
- Tapering concavely to a point.
-
- acute
- Tapering with straight or slightly convex sides
to a point.
-
- anther
- The free end of the stamen that bears pollen;
pollen sac.
-
- apex
- Tip of a leaf or flower.
-
- apiculate
- Having a short, sharp point.
-
- axillary
- The angle between the stem and leaf.
-
- azalea
- Azaleas are found in subgenera Pentanthera and
Tsutsusi of genus Rhododendron. These subgenera are commonly referred to
as deciduous and evergreen, respectively. Azalea leaves are typically
thin, flexible while leaves elsewhere in the genus tend to be leathery.
Deciduous azaleas are so called because they drop their leaves in the fall or
winter. Evergreen azaleas have two kinds of leaves: spring leaves emerge
at or after time of flowering; summer leaves (usually smaller and somewhat
thicker) emerge midsummer and remain on the plant through the winter.
Another important difference is that the terminal buds of deciduous azaleas
produce only flowers; those of evergreen azaleas produce new vegetative shoots
as well as flowers.
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B |
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- bi-generic
- Hybrid with parents in two different genera.
-
- blade
- Extended portion of a leaf.
-
- blotch
- Area of contrasting color on the uppermost
petal(s) of some plants. (See also spotting.)
-
- bract
- A modified leaf or bud covering.
-
- bristle
- A slender, stiff hair.
-
- bullate
- Puckered or quilted appearance.
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C |
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- calyx
- Outer whorl of floral envelopes, composed of
sepals.
-
- campanulate
- Bell-shaped, cup-shaped.
-
- capsule
- Seed pod.
-
- cilia
- Small hairs, often present on leaf margins.
-
- clone
- A genetically identical plant resulting from
asexual propagation (cuttings, layering, grafting, or tissue culture).
-
- conic
- Cone shaped, conical
-
- convex
- Curved outward.
-
- cordate
- Heart-shaped, two rounded basal lobes separated
by a deep depression.
-
- coriaceous
- Leathery in texture.
-
- corolla
- The floral envelope inside the calyx, composed
of a whorl of petals.
-
- cultivar
- Shortened form of cultivated variety.
A group of plants, selected for particular attributes, that are clearly
distinct, uniform, and stable and that retain these characteristics when
propagated by appropriate means.
-
- cuneate
- Wedge-shaped acute angle at the leaf base.
-
- cutting
- New growth cut for rooting or other vegetative
propagation.
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D |
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- deciduous
- Shedding their leaves at the end of the growing
season.
-
- declinate
- Bent or curved downward or forward.
-
- deflexed
- Bent abruptly downward.
-
- double
- Having more than one set of petals or petal-like
structures, or with petaloid stamens.
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E |
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- elepidote
- Without scales, as opposed to lepidote (with
scales).
-
- elliptic
- Oblong with rounded ends.
-
- endemic
- Native or confined naturally to a given
geographical area.
-
- epiphyte
- A plant growing non-parasitically upon another.
-
- ericaceous
- Belong to the family Ericaceae, which
includes rhododendrons, heathers, mountain laurel, blueberries, etc.
-
- evergreen
- Bearing green foliage throughout the year.
- exserted
- projecting beyond, such as stamens projecting
from the corolla
-
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F |
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- family
- A group of genera sharing certain
characteristics.
-
- feral
- Wild or escaped from domestication and able to
reproduce normally.
-
- filament
- The thread-like stalk of a stamen.
-
- flower
- The specialized reproductive structure of a seed
plant. Rhododendrons have flowers, not florets.
-
- form,
pl. formae
- A minor variation within
a species that is sufficiently distinctive to warrant recognition as a separate
taxon. In cultivated plants, it is current practice to name these forms as
cultivars.
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G |
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- genus, pl. genera.
- A taxonomic group comprising closely related
species.
-
- glabrous
- Hairless
-
- glaucous
- Having a gray or whitish cast, covered with a
bluish, gray, or white bloom.
-
- globose
- Nearly spherical.
-
- grex
- All the seedlings of a particular cross.
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H |
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- habit
- General form of a plant.
-
- hardiness
- Cold hardiness is the lowest temperature a plant
can tolerate without damage.
-
- hirsute
- With rough or coarse, more or less, erect hairs.
-
- hose-in-hose
- A double flower having floral envelopes (whorls
of petals or petal-like structures) nested one within the other. The term
relates only to appearance, not to the morphology of the structures.
-
- hybrid
- Usually a cross between different clones within
a species (intraspecific hybrid) or between clones from different species.
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I |
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- indumentum
- A wooly or hairy covering of leaves or young
shoots. Can be on both top and bottom surfaces of new or young leaves, but
is usually confined to the underside of mature leaves.
-
- inflorescence
- An arrangement of flowers on a stem or axis, it
may comprise a cluster of flowers or a single flower.
-
- involute
- Rolled inward or toward the upper side.
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J |
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K |
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L |
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- lamina
- Blade of a leaf.
-
- lanceolate
- Shaped like a lance head, widening above the
base and tapering toward the apex.
-
- lax
- Not rigid, loose.
-
- lepidote
- Having scales. Tiny scales typically cover
the undersides of the leaves. Characteristic used to separate the genus
rhododendron into two major groups.
-
- lobe
- A rounded division of a flower or leaf.
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M |
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- margin
- Leaf or flower edge.
-
- mucronate
- Having a leaf tip terminating in a hard point
that is a continuation of the midvein.
-
- mutation
- An inheritable change in genetic material.
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N |
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- nectary
- Nectar secreting gland at the base of the
corolla.
-
- nervate
- Leaves with prominent ribs or veins.
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O |
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- obovate
- Egg-shaped with the broadest part towards the
apex.
-
- oblanceolate
- Widest near apex, tapering to base, longer than
wide.
-
- oblong
- Much longer than wide, with sides roughly
parallel for most of their length.
-
- orbicular
- Flat with the outline circular or nearly
circular; disc shaped.
-
- ovate
- Egg-shaped with the broadest part towards the
base.
-
- ovary
- Seed bearing part of the pistil.
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P |
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- pedicel
- The stalk of an individual flower in an
inflorescence.
-
- pendulous
- Hanging down, drooping.
-
- petal
- One division of the corolla.
-
- petaloid
- like or consisting of petals.
-
- petiole
- The stack of a leaf.
-
- pH
- A measure of acidity or alkalinity. A pH
of 7.0 is neutral. Smaller numbers indicate acidity, larger numbers indicate
alkalinity. Rhododendrons, like other members of the heath family, favor soils
which are mildly acidic with a pH around 5.5.
-
- pistil
- The female organ of a flower consisting of
ovary, style and stigma.
-
- pollen
- Minute powder-like grains borne by the anther.
Pollen contains the male gametophyte of a plant.
-
- precocious
- Flowering before the leaves appear.
-
- pubescent
- Covered with soft, short hair.
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Q |
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- quadrate
- Square
or nearly square.
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R |
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- recurved
- Curved backward or downward.
-
- revolute
- Rolled back or downward from the margins.
-
- rhododendron
- Genus of shrubs in the Ericaceae family (from
Greek rhodo meaning rose and dendron meaning tree). In
common usage, "rhododendron" usually refers to members of the subgenera
Rhododendron
and Hymenanthes, as distinct from the azaleas.
-
- rotate
- Wheel shaped, saucer-like
-
- rugose
- Wrinkled.
-
- rugulose
- Lightly wrinkled.
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S |
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- section
- A division of classification. Sections and
subsections are taxonomic groups between genus and species.
-
- scale
- Tiny, plate-like structures appearing on leaves
and other plant parts.
-
- sepal
- Lower flower part, the calyx.
-
- series
- A category in an outdated system of rhododendron
classification.
-
- sessile
- Without a stalk.
-
- spatulate
- Shaped like a spatula, spoon or paddle.
-
- species
- Basic classification unit of plants comprised of
individuals that are recognized as distinct from other species, and which can
freely interbreed among themselves.
-
- sport
- A naturally occurring mutation which usually
appears spontaneously with characteristics which differ from the rest of the
plant, such as different flower color, variegated leaves, etc.
-
- spotting
- Dots or spots, usually of darker color,
sometimes found on the upper petal(s) of some rhododendrons and azaleas.
-
- stamen
- The male organ of a flower consisting of an
anther on a filament.
-
- stigma
- The tip of the pistil, usually sticky, which
receives the pollen for fertilization of the ovule.
-
- strigose
- Rough with straight, short sharp appressed
hairs.
-
- subgenus
- The principal subdivision of a genus.
-
- suborbicular
- Not quite circular
-
- subsection
- See section.
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T |
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- taxonomy
- Classification (based on study of morphology,
geographic distribution, phylogeny) and nomeclature.
-
- throat
- The base opening of the corolla.
-
- tomentose
- Covered with matted, wooly hair.
-
- tomentum
- Matted wooly hairs on stems, leaves or seeds.
-
- truss
- Flower cluster (inflorescence) made up of many
individual flowers. The structure varies considerably among species and
cultivars, giving the plants a distinctive appearance.
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U |
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- undulate
- Wavy
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V |
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- variety
- A naturally occurring group within a species
that is distinct enough to warrant taxonomic recognition but not sufficiently
distinct to be segregated as another species.
-
- vein
- A vascular bundle in a leaf blade or petal.
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W |
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- whorl
- Three or more leaves or branches at a node;
circle of flower parts as sepals, petals or stamens.
-
- woolly
- Clad with long, soft more or less or matted
hairs.
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X |
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- xylem
- Tissues in plants through which water and food
is conveyed up the stem from the roots, also furnishing support of the plant.
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Y |
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Z |
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American Rhododendron Society
Executive Director: P.O. Box 525, Niagara Falls, NY 14304
Ph: 416-424-1942 Fax: 905-262-1999 E-Mail:
lauragrant@arsoffice.org
©1998-2008, ARS, All rights reserved.
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