Objectives for this lab are to: 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

Basic Concepts
Dissection Exercise

Basic Concepts

Parts of a Flower

Pedicel--the stalk of an individual flower
Sepal--one member of the outermost whorl of a flower. Collectively, the sepals make up the calyx. The sepals may be free or fused.
Petal--one member of the second whorl of a flower. Collectively, the petals make up 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 together
Stamen--one member of the whorl of male sex parts. Each stamen consists of a filament and anther, where pollen is produced. Collectively, the stamens make up the androecium.
Tetradynamous--refers to four long and two short stamens in one flower
Monadelphous--refers to stamens united by the filaments into one column
Diadelphous--refers to stamens united by the filaments into two groups--often 1 in one group and 9 in another
Carpel--one member of the whorl of female sex parts. Collectively, the carpels make up the gynoecium. Each carpel consists of an ovary connected to a stigma by a style. The stigma is receptive to pollen. Within the ovary, on the placentae (sing., placenta) are one or more ovules, which will mature into seeds. The open spaces inside the ovary are called locules or cells. The dividing walls are called septa.
A gynoecium of many separate carpels is termed apocarpous. The flower is said to have many simple pistils
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
The term pistil is also used. It refers to a single carpel if there is only one, or to the whole structure if the carpels are united.

Ovary Position

Hypogynous--The flower is hypogynous if the ovary is situated above the calyx and there is no floral cup around it. The ovary is superior.
Perigynous--The flower is perigynous if the ovary is situated within (and free from) a floral cup or hypanthium. The ovary is superior.
Epigynous--The flower is epigynous if the ovary is situated below the calyx. The ovary is inferior. (In the graphic example, the calyx is pink and the flower hangs upside down.)

Floral Symmetry

Actinomorphic--the flower has many axes of symmetry, e.g. no matter where you "cut it in half", 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.
Zygomorphic--the flower has only one line of symmetry, e.g. there is only one way to divide it to get equal halves. Also called bilaterally symmetrical or irregular, though some texts reserve "irregular" for flowers with no axis of symmetry, such as Canna.

Perianth shape (usually applied to corolla, but may be applied to calyx)

Rotate--shallow and relatively flat or dish-shaped
Stellate--star-shaped  (this is not as commonly used as some other terms)
Urceolate--urn-shaped; somewhat flared out or inflated and then narrowed at the opening
Campanulate--bell-shaped, with the segments gently flaring
Tubular--parts fused into a usually slender, uniform tube, usually with the free tips proportionately small and/or only slightly spreading
Funnelform--with parts fused into a tube that widens gradually from base to tip
Salverform-- with a narrow tube and an abruptly expanded, spreading portion which is often called the limb.  Here is another example.
Bilabiate--two-lipped (like a sock puppet); usually the perianth parts are fused at least below.  Here is another example.
Geniculate-- with an "elbow" or bend where the perianth changes direction suddenly
Papilionaceous--from 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 labeled image.
Spurred--with a spur-- a hollow, usually nectar-bearing, backward or downward extension of a sepal or petal.  A flower may have more than one. Spurs may be short as in Viola (spur is at the top of the flower, behind the pedicel)
Ligulate or Ray--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
Cruciform--cross-shaped, with four petals arranged at right angles. 
Galeate--with a galea or hood.  Applies to flowers in which the upper lip is drawn forward, over, and often down.  Here is another example.
Gibbous--bulging or inflated (this example is only mildly gibbous, but you can see that the flower is expanded more on one side than the other)
Personate--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)
Fenestrate--(from 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.

Inflorescence Types

Solitary--just one flower on the peduncle
Spike--one unbranched axis and the flowers sessile (without pedicels)
Spadix--like a spike, but fleshy and the flowers usually reduced and unisexual. Often subtended by a bract called a spathe
Spikelet--like a spike, but with the flowers and inflorescence subtended by specialized bracts. Usually applied to the grass family (Poaceae)
Raceme--one unbranched axis and the flowers with pedicels
Corymb--like 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 arrangement of heads
Umbel--all the pedicels arise from one point at the top of the peduncle
Compound umbel--peduncles arise from one point and each in turn bears a smaller umbel. Common in the carrot family (Apiaceae)
Cyme---a central flower opens first and later flowers are borne on branches below it. Some cymes are one-sided. Some are scorpioid cymes, i.e. curled like a scorpion's tail.
Verticil or Whorl--the flowers are borne in a tight circle at each node
Panicle--the main axis has branches which are in turn rebranched
Head--many small flowers borne on a common receptacle; may look like a single flower. Common in the sunflower family (Asteraceae)

Fruit Types

Dry, indehiscent fruits
Achene--one seed which is free of the pericarp (fruit wall)
Samara--an achene with a wing for wind dispersal
Caryopsis or Grain--one seed which has the seed coat fused to the pericarp
Nut--one seeded by abortion (only one ovule matures), usually hard-shelled.  A small nut is a nutlet

Dry, dehiscent fruits
Follicle--from one simple pistil, dehisces along one suture
Legume--from a simple pistil, dehisces along two sutures
Capsule--usually from a compound pistil, usually many-seeded.  Capsules show various means of dehiscence

• Loculicidal-- dehisces into the locules and between the septa, breaking along the back of each carpel
  
• Septicidal-- dehisces through the septa between the carpels
  
• Poricidal --opens by holes like a salt shaker
  
• Valvate (fig. 3 in image) or denticidal --opens by means of teeth or valves at the top
  
• Circumscissile--dehisces in a line around the top, with the top falling away in one piece (fig. 6).  This sort of fruit is sometimes called a pyxis
  

Silique or silicle--special capsule with two halves which fall away from a central false septum (replum) to which the seeds are attached. Found in the mustard family (Brassicaceae). Siliques are long and thin; silicles are short and fat.
Schizocarp--from a compound pistil, splits into mericarps (pieces) which enclose one or more seeds and resemble fruits themselves. The link shows a maple fruit, which will split into two samara-like mericarps.)

Fleshy fruits
Drupe--from a simple pistil, one seed within a stony endocarp
Berry--from a compound pistil, few to many seeds
Pepo--a berry with a hard, leathery rind, usually applied to fruits in the squash family (Cucurbitaceae)
Hesperidium--a berry with an aromatic leathery rind; inside divided into segments; a citrus fruit (Rutaceae)
Hip--mature hypanthium containing achenes derived from multiple simple pistils, e.g. a rose fruit
Pome--from an inferior ovary with the hypanthium/receptacle tissue swollen and juicy. 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 of 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 receptacle.
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 this category.

Placentation Types

Marginal--ovules arranged along the suture of a single, simple pistil (cross-section)
Axile--a separate locule for each carpel and the ovules attached to placentae in the middle where the septa come together (cross-section)
Parietal--ovules attached to the wall of a unilocular ovary (cross-section)
Free-central--ovules attached to a peg or stalk that arises from the ovary floor but which does not reach the roof; ovules usually few to many (long-section)
Apical--ovules attached to the roof of the ovary (long-section)
Basal--ovules attached to the floor of the ovary (long-section) Go on to the Dissection Exercise
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last updated 20 July 2007 by MDR