Laboratory 3: Reproductive Characters
This lab covers the reproductive parts of flowering
fruits, and seeds. This lesson can be divided into two parts:
Most of this material is linked to images; some is not.
topic is covered fully in Vascular Plant Taxonomy by
|Objectives for this lab are to:
Safety concerns for this
lab: Use caution with dissecting tools, wear goggles if working
with specimens preserved in Carosafe, dispose of Carosafe specimens in
proper waste container
- become familiar with a dissecting scope and its features
- learn definitions for reproductive terms (look for bold words in this lab)
- learn to identify and count the parts of a flower
- learn to interpret floral symmetry, fusion of floral parts,
and ovary construction
- learn to write and interpret floral formulas
- learn inflorescence types
- learn fruit types
- practice keying skills
Parts of a Flower
stalk of an individual flower
member of the outermost whorl of a flower. Collectively, the sepals
up the calyx. The sepals may be free or fused.
member of the second whorl of a flower. Collectively, the petals make
the corolla. The petals may be
free (the flower then termed polypetalous) or
fused into one piece (the flower then termed sympetalous).
Perianth--the calyx and corolla
Stamen--one member of the whorl of male
sex parts. Each stamen
consists of a filament and anther, where pollen is
Collectively, the stamens make up the androecium.
to four long and two short stamens in one flower
Carpel--one member of the whorl of
sex parts. Collectively, the carpels make up the gynoecium.
carpel consists of an ovary
connected to a
stigma by a
style. The stigma is receptive to pollen. Within the ovary, on the
placenta) are one or more
ovules, which will mature into seeds. The open spaces inside the
are called locules
or cells. The dividing walls are called septa.
to stamens united by the filaments into one column
to stamens united by the filaments into two groups--often 1 in one
and 9 in another
A gynoecium of many separate carpels is termed apocarpous.
The flower is said to have many simple pistils
The term pistil is also used. It
to a single carpel if there is only one, or to the whole structure if
carpels are united.
A gynoecium of many fused carpels is termed
syncarpous. The flower is said to have a compound pistil
A gynoecium with only one carpel is termed unicarpellate.
The flower has a simple pistil
flower is hypogynous if the ovary is situated above the calyx and there
is no floral cup around it. The ovary is superior.
flower is perigynous if the ovary is situated within (and free from) a
floral cup or hypanthium. The ovary is superior.
flower is epigynous if the ovary is situated below the calyx. The ovary
is inferior. (In the graphic example, the calyx
pink and the flower hangs upside down.)
flower has many axes of symmetry, e.g. no matter where you "cut it in
the halves will match. Also called regular or radially
symmetric. Note that this does not have to do with number of parts. A
flower with an odd number of parts may still be actinomorphic if the
parts are all the same size and shape and uniformly arranged/spaced.
flower has only one line of symmetry, e.g. there is only one way to
it to get equal halves. Also called bilaterally symmetrical or irregular,
though some texts reserve "irregular" for flowers with no axis
symmetry, such as Canna.
Perianth shape (usually applied to
corolla, but may be applied to calyx)
and relatively flat or dish-shaped
(this is not as commonly used as some other terms)
somewhat flared out or inflated and then narrowed at the opening
with the segments gently flaring
fused into a usually slender, uniform tube, usually with the free tips
parts fused into a tube that widens gradually from base to tip
with a narrow tube and an abruptly expanded, spreading portion which is
often called the limb.
(like a sock puppet); usually the perianth parts are fused at least
below. Here is another
with an "elbow" or bend where the perianth changes direction suddenly
the French word for "butterfly." Applied to members of the
Fabaceae in which the flower has one large petal, the banner or standard
, two similar side
petals called wings
, and two
folded or usually fused-together lower petals called the keel. Here is a
a spur-- a hollow, usually nectar-bearing, backward or downward
extension of a sepal or petal. A flower may have more
Spurs may be short as in Viola
(spur is at the top of
the flower, behind the pedicel)
--zygomorphic and with all the petals pulled to one side into a
flat, strap-like structure. Typical of the sunflower family,
e.g., the "petals" of a daisy
LESS COMMONLY ENCOUNTERED TERMS
with four petals arranged at right angles.
a galea or hood. Applies to flowers in which the upper lip is
drawn forward, over, and often down. Here is
or inflated (this example is only mildly gibbous, but you can see that
the flower is expanded more on one side than the other)
--with an arched upper lip and a lower lip that pushes up
into the throat of the flower, forming a "palate" (The flowers in
the image are also spurred)
the French for "window") with the parts fused into a tube and with a
"window" or unfused opening in the side of the tube. Typical of Lobelia.
NOTE: That the above
terms may be combined. For example, a corolla may be both
bilabiate and geniculate, or it could be tubular and spurred, etc.
For each, the stalk of the inflorescence is called the peduncle
and the stalk of an individual flower is the pedicel.
one flower on the peduncle
unbranched axis and the flowers sessile (without pedicels)
a spike, but fleshy and the flowers usually reduced and unisexual.
subtended by a bract called a spathe
a spike, but with the flowers and inflorescence subtended by
bracts. Usually applied to the grass family (Poaceae)
unbranched axis and the flowers with pedicels
a raceme, but the pedicels all elongating to the same level to give the
inflorescence a flat-topped appearance. The link shows a corymb-like
the pedicels arise from one point at the top of the peduncle
umbel--peduncles arise from one point and each in turn bears a
umbel. Common in the carrot family (Apiaceae)
central flower opens first and later
flowers are borne on branches below it. Some cymes are one-sided. Some
cymes, i.e. curled like a scorpion's tail.
or Whorl--the flowers are borne in a tight circle at each node
main axis has branches which are in turn rebranched
small flowers borne on a common receptacle; may look like a single
Common in the sunflower family (Asteraceae)
Fruits can be categorized according to whether they are dry or fleshy
whether or not they dehisce (split open) at maturity
Dry, indehiscent fruits
seed which is free of the pericarp (fruit wall)
achene with a wing for wind dispersal
or Grain--one seed which has the seed coat fused to the pericarp
seeded by abortion (only one ovule matures), usually
hard-shelled. A small nut is a nutlet
Dry, dehiscent fruits
one simple pistil, dehisces along one suture
a simple pistil, dehisces along two sutures
from a compound pistil, usually
many-seeded. Capsules show various means of dehiscence
or silicle--special capsule with two halves which fall away from a
central false septum (replum) to which the seeds are attached.
in the mustard family (Brassicaceae). Siliques are long and thin;
are short and fat.
a compound pistil, splits into mericarps (pieces) which enclose
one or more seeds and resemble fruits themselves. The
shows a maple fruit, which will split into two samara-like mericarps.)
a simple pistil, one seed within a stony endocarp
a compound pistil, few to many seeds
berry with a hard, leathery rind, usually applied to fruits in the
berry with an aromatic leathery rind; inside divided into segments; a
hypanthium containing achenes derived from multiple simple pistils,
e.g. a rose fruit
an inferior ovary with the hypanthium/receptacle tissue swollen and
E.g., in an apple, the part one eats is the hypanthium/receptacle--the
mature ovary is actually just the core.
Other types of fruits
Aggregate--fruit composed of mature ovaries
from separate pistils of ONE flower. Can be an aggregate of achenes,
drupelets, samaras, etc.
Multiple--fruit composed of mature ovaries
from separate pistils from SEVERAL flowers. Can be a multiple
follicles, drupelets, etc. A
pineapple is a multiple of berries. A fig is a special type
of multiple called a syconium,
in which the flowers are borne on the inside of an enlarged, hollow
Accessory--fruit where the "fruit" part is
derived from something other than ovary tissue. E.g., a
strawberry is a swollen receptacle; the "seeds" on the surface are
the true fruits, achenes. Some put hips and pomes in
Placentation refers to the pattern of attachment of ovules within the
arranged along the suture of a single, simple pistil (cross-section)
separate locule for each carpel and the ovules attached to placentae in
the middle where the septa come together (cross-section)
attached to the wall of a unilocular ovary (cross-section)
attached to a peg or stalk that arises from the ovary floor but which
not reach the roof; ovules usually few to many (long-section)
attached to the roof of the ovary (long-section)
attached to the floor of the ovary (long-section)
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last updated 25 June
2010 by MDR