Floral Morphology, cont.

I. Fusion and Evolution of floral parts.

A. Fusion of like parts (e.g. sepals with sepals) is called connation

B. Fusion of unlike parts (e.g. stamens to petals) is called adnation.

A. sepals not fused (free) = aposepalous

B. sepals fused to each other = synsepalous

A. petals not fused = apopetalous

B. petals fused to each other = sympetalous. Sometimes called the corolla tube.

C. symmetry

1. actinomorphic = radially symmetrical (Isopyrum, Crassula)

2. zygomorphic; for here, = bilaterally symmetrical (Viola)

3. irregular, = no symmetry (Calathea)

D. Shape descriptions

1. actinomorphic corollas (radially symmetrical)

• funnelform (Ipomoea purpurea)
• salverform (Ipomoea multifida)
• campanulate (Platycodon)
• urceolate (Pieris, Vaccinium)
• rotate (Myosotis)
• actinomorphic corollas (from Lawrence)

2. zygomorphic corollas (bilaterally symmetrical)

• bilabiate (Salvia)
• galeate = helmet shaped (Pedicularis)
• papilionaceous (Lathyrus, Lupinus)
• ligulate [in sunflower family, Asteraceae] (Tragopogon, Taraxacum)
• spurred (Impatiens, Utricularia)
• zygomorphic corollas (from Lawrence)

A. Number and type of stamens - not fused to each other (= free)

1. didynamous = 2 long + 2 short (Campsis)
2. tetradynamous = 4 long + 2 short (Barbarea, Brassica)

B. Stamen connation

1. monadelphous = filaments fused into tube (Hibiscus, Gossypium)
2. diadelphous = 9 filaments fused, 1 free (Rhynchosia)
3. synandrous = syngenesious; anthers fused (Aeschynanthus, Monarda) 
4. androecium types (from Lawrence)

C. Attachment of anther to filament

1. basifixed (Stylophorum, Sassafras)
2. dorsifixed and versatile (Tecomaria)

D. Anther dehiscence

1. porose (Vaccinium, Kalmia)
2. slits (Tecomaria)
3. valves or flaps (Lindera, Sassafras)

E. Vestigial or non-functional stamen = staminode (pl. -ia) (Acer platanoides)

A. Degree of fusion

1. carpels free - apocarpous (Drimys, Magnolia, Crassula)
2. carpels connate = syncarpous; produces a compound ovary (Narcissus, Oenothera)
3. gynoecial types (from Lawrence)

B. Ovary position (w/ resp. to point of insertion of the floral parts) - see lab manual.

1. Hypogynous = ovary superior.
   
   • All whorls free (except G) (Pelargonium)
   • CO & A adnate, A connate (Hibiscus)
   • CO & A adnate (Convolvulus tricolor)
   • CA & CO adnate. (Aesculus)
   • with a Hypanthium = CA, CO, & A adnate (Rosa)
   • CA & A adnate (CO missing) (Dirca palustris)
2. Half inferior.
   
   • Whorls free above ovary. (Philadelphus)
3.  Epigynous = ovary inferior.
   
   • CA & CO  free above ovary. (Cornus)
   • CA & CO  free above ovary, stamens monadelphous (Eucnide)
   • CO & A adnate above ovary. (Viburnum)
   • CA, CO, & A adnate above ovary (hypanthium) (Fuchsia)

C. Placentation = ovule position inside carpel

1. axile (Asarum, Sarracenia, Rhododendron)
2. parietal (Viola, Eucnide, Stylophorum)
3. free central (Dodecatheon, Agrostemma)
4. basal (Arisaema)
5. marginal or lateral (Drimys)
6. apical or pendulous (Ulmus)
7. placentation types 1, 2 (from Lawrence)

D. Ovule types

1. orthotropous. Funiculus attached at chalazal end, ovule not curved, funiculus and micropyle on opposite sides (Arisaema, Carya, Eucnide)
2. amphitropous. Funiculus medially attached, ovule curved on both sides, thus retaining a straight axis, funiculus partly fused to exterior of ovule (Abutilon, Arabidopsis)
3. anatropous. Funiculus attached basally near funiculus, ovule curved 180 degrees (Narcissus, Asarum, Canna)
4. campylotropous. Funiculus attached medially, ovule curved on one side (Agrostemma)
5. ovule types (from Lawrence)

SIUC / College of Science / Elements of Plant Systematics

URL: http://www.plantbiology.siu.edu/PLB304/Lecture10FloralMor/Floralmorph2.html

Last updated: 15-Feb-09 / dln