Flowers are borne on structures which are referred to as
inflorescences. An inflorescence is a collection of individual
flowers arranged in some specific fashion. The following are some of
the representative types found in both woody and herbaceous plants.
Spike. Individual flowers are sessile on the elongated axis
(peduncle). The --male flower of Betula, Carpinus, Alnus, Populus,
Quercus, Salix and Catya
are spikes with a special name termed catkin or ament
(Indeterminate).
Raceme. In the simplest terms it is a modification of a spike with
the individual
flowers stalked (on a pedicel). Cladrastis, Laburnum, Wisteria
possess racemose flowers (Indeterminate).
Corymb. An indeterminate (can continue to elongate) inflorescence in
which the individual flowers are attached at different points along
the peduncle. The outer flowers open first. Ma/us, Prunus, and
Iberis show corymb inflorescences.
Umbel. An indeterminate inflorescence in which the pedicels of the
in¬dividual flowers radiate from about the same place at the top of
the peduncle. Flowers open from outside in. l-Iedera helix, Aralia,
Daucus (carrot) are examples.
Cyme. A determinate, flat or convex inflorescence, the central or
inner flowers opening first. Comus, Viburnum, Geranium are examples.
Panicle. An indeterminate inflorescence with repeated branching.
Panicles can be made up
of many racemes, spikes, corymbs, cymes, or umbels.Racemose-panicles
are found in P/ens, Koelreuteria; spikose-panicles in corn;
corymbose-panicles in Pyracantha; umbellose-panicles in Aralia.
Solitary. Indicates a single flower with a pedicel attached to the
stem. Magnolia, Calycanthus, Kerr/a and many other woody plant
flowers fall into this category.
Head. The typical inflorescence
of the family Asteraceae (Compositae). Made up of ray (sterile) and
disk (fertile) flowers which are arranged on a flattened receptacle.
Chrysanthemum, Rudbeckia are ex¬amples.
A spadix is a specialized type of inflorescence typical of many
tropical plants. The showy part is the bract or spathe while the
spike-like structure which is partially surrounded by the spathe
bears the fertile flowers. Examples in¬clude Anthunium,
Spathiphyllum, Caladium, Calla and Philodendron.
FRUIT MORPHOLOGY
The longitudinal section of the ‘typical” flower offers a
representative view of the ovary. The ovary is the forerunner of the
fruit and is defined as an unripened fruit. The ovary is composed of
carpel(s) which are highly modified leaf-like structures which
inclose ovules (forerunner of seeds). An ovary may be composed of
one carpel (simple fruit) or two or more carpels (compound fruit).
Fruits are very important considerations in woody landscape plants
for they offer good ornamental assets (color, texture) and positive
identification features through late summer, into fall, and often
persist until spring of the year following maturation. The fruits of
hex (Holly) are often colorful for a long period of time while
fruits of Prunus (Cherry), some
Malus (Flowering Crabapples), and
several Crataegus (Hawthorns) persist briefly after ripening (2 to 4
weeks).
The following classification scheme for fruits along with their
definitions and line drawings should afford an idea of the diversity
of fruit types which are manifested by woody or herbaceous plants.
I. SIMPLE FRUITS
A. Dry Fruits
1. indehiscent fruits (not splitting open at maturity)
a. Achene — one-seeded fruit with seed attached at only one place to
the pericarp. Pericarp is very close-fitting and does not split
open, at least along regular established lines. Examples: Buckwheat,
Sunflower, Calendula.
b. Caryopsis — similar to an achene but the pericarp is adherent to
the seed, the two often being indistinguishable (seed coat is
inseparable from the pericarp). Examples: Corn, Wheat.
c. Samana — usually one-seeded (not always) with a membranous wing
which develops from the pericarp. Examples: Maple, Ash, Elm.
d. Nut — a bony, hard, one-seeded fruit. The pericarp is bony
throughout. Examples: Oak, Chestnut and Filbert.
e. Utnicle — similar to an achene but the ovary wall is relatively
thin and inflated so it fits only loosely around the seed. Examples:
Goosefoot, Pigweed.
f. Nutlet — diminutive of nut. Examples: Hornbeam, Birch,
Hophornbeam.
2. Dehiscent fruits (splitting open when mature)
a. Legume (Pod) — composed of one carpel and opens along two
sutures; characteristic of most members of the Fabaceae (Leguminosae);
contains several to many seeds- Ex¬amples: Redbud, Honey-locust,
Coffeetree, Black Locust.
b. Follicle — composed of one carpel but splits open at maturity
along one suture exposing several to many seeds. Examples: Larkspur,
Columbine, Peony, Milkweed, Spirea, in¬dividual fruits of Magnolia.
c. Capsule — many-seeded fruits formed from more than one carpel.
The carpels are united. Locuhicidal Capsule opens along midrib;
Septicidal Capsule divides through the parti¬tions. Examples:
Rhododendron, Mockorange, Deutzia, Forsythia, and Lilac.
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d. Si/ique — composed of two carpels which separate at maturity,
leaving a thin partition between. Example: Mustard family.
e. Si//ole — a short, broad silique. Examples: Shepherd’s Purse,
Peppergrass.
f. Pyxis — type of capsule which opens around a horizontal ring, the
top of fruit falling away like a lid. Example: Purslane.
B. Fleshy Fruits
1. Bert’, — the entire pericarp (exo, endo, meso-carp) is fleshy.
Examples: Tomato, Date, Banana, Blueberry, Cranberry, Honeysuckle.
a. Hespenidium — a berry with a leathery rind. Examples: Orange,
Lemon, Grapefruit.
b. Pepo — a berry with a hard rind and fleshy inner matrix.
Examples: Watermelon, Squash, Pumpkin.
2. Drupe — the pericarp is clearly differentiated into three layers;
exocarp is the epidermis; middle layer, the mesocarp, is fleshy; and
the inner layer, the endocarp, is stony. Examples:
Cherry, Peach, Plum, Sassafras, Viburnum, Holly and numerous other
woody ornamental plants.
3. Pome —the pericarp is surrounded by the floral tube (hypanthium)
which becomes fleshy and tasty. Examples: Apple, Pear, Quince.
II. AGGREGATE FRUITS
Develop from a single flower which contains many pistils. Several to
many fruitlets are massed on one receptacle. Examples:
Raspberry—aggregate of drupes; Strawberry—aggregate of achenes;
Tuliptree—aggregate of samaras; Magnolia—aggregate of follicles;
Osageorange—aggregate of drupes.
III. MULTIPLE FRUITS
Consists of several flowers which are more or less united into one
mass. Examples: Fig, Pineapple, Mulberry.
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