Vascular Plant Systematics - Fall 2001
Lecture #3 - Reproductive Morphology of Flowering Plants
Reproductive Morphology - much of the classification of flowering plants is based on
reproductive structures - and a knowledge of flowers, fruits and seeds is essential to identifying
plants.
** - A flower is a highly modified shoot with specialized appendages. Flowers may arise in the
axil of a leaf or, more often, in the axil of a reduced leaf called a bract. Ripened ovaries in the
flower develop into the fruit. Fruits may have other floral structures associated with them and
normally contain seeds, which are ripened ovules.
Flower Parts
http://www.enchantedlearning.com/subjects/plants/printouts/floweranatomy.shtml
androecium - the male part of the flower; a collective name for the stamens of a flower (and the
parts derived from stamens).
Anther - the part of the stamen where the pollen is produced
calyx - the collective name for the sepals; occupies the outermost position of a flower; usually
green but sometimes other colors (e.g., such as in lilies)
carpel - that part of a pistil formed from one sporophyll in the evolutionary development of a
flower; a simple pistil from a single sporophyll; one part of a compound pistil
corolla - the inner part of the perianth - all of the petals collectively. The corolla is usually larger
than the calyx and is often brightly colored.
filament - stalk-like part of the stamen that supports the anthers and which is attached to the
receptacle; it may be fused to the petals for part of its length or fused to each other
fruit - mature ripened ovary or ovaries containing seeds (ovules)
gynoecium - the female part of the flower; the collective term for the carpels or pistils. It is the
innermost part of the flower and is composed of one or more carpels ..... which may or may not
be united into a compound pistil
hypanthium - a floral cup or tube formed either from the receptacle or from fusion of the bases
of the sepals, petals, and stamens or both
ovary - the usually enlarged, basal portion of the pistil where the ovules are born
ovule - the structure in the ovary which develops into the seed
pedicel - the stalk of each individual flower
peduncle - the stalk bearing the entire inflorescence or a solitary flower
perianth - collective term for the floral envelope; calyx and corolla combined
petals - the individual parts of the corolla occupying a position between the sepals and stamens
pistil - a structure composed of one or more carpels and usually having a stigma, style, and
ovary. The carpels in a flower are collectively termed the gynoecium.
receptacle - the portion of the stem which bears flower parts (base of a flower which forms a
portion of the fruit in some species
seed - mature ovule consisting of a seed coat and an embryo
sepals - individual components of the calyx; outermost whorl of the flower. The sepals are
usually green, but may be petaloid or colored
stamens - the pollen-producing part of the flower, located just inside the corolla. All the stamens
= androecium.
staminode - sterile stamen
stigma - portion of the style that is receptive to germination of pollen
style - the elongated stalk connecting the stigma to the ovary
Peduncle vs. Pedicel
*** - note - the number of carpels in a flower is usually equal to the number of stigma lobes,
styles, locuoles or placentae.
Inflorescences (the arrangement of flowers on the plant)
check out: http://web1.manhattan.edu/fcardill/plants/angio/topics.html or
http://www.snr.uvm.edu/www/mac/plant-id/id/floral.html
corymb - a broad inflorescence in which the lower pedicels are successively elongate, giving the
inflorescence a flat-topped appearance.
cyme - a flower cluster often convex or flat topped in which the central or terminal flower
blooms the earliest.
panicle - a compound inflorescence in which the main axis is branched one or more times and
may support spikes, racemes, or corymbs.
raceme - an inflorescence with a single axis with the flowers arranged along the main axis or
pedicels.
umbel - a convex or flat-topped inflorescence in which the flowers are all arising from a single
point the younger ones in the center
simple umbel vs. compound umbel
spike - an inflorescence with a simple axis and flowers without pedicels
head - usually associated with a composite a dense cluster of stalkless flowers
solitary flower - a single flower atop a single stalk or peduncle
Numerical Plan - most families of dicotyledons have a floral numerical plan of 4 or 5, or in
multiples of 4 or 5. Monocotyledons typically have floral parts found in 3s or multiples of 3s.
Symmetry - the perianth of some flowers is so arranged that any line bisecting the flower
through the central axis will produce symmetrical halves. Flowers having this radial symmetry
are referred to as regular or actinomorphic. Other plants have flowers that may be divided into
symmetrical halves only on one line. These flowers have a bilateral symmetry and are referred
to as being irregular or zygomorphic (e.g., mints, snapdragons, pea flowers).