EVOLUTIONARY TRENDS OF FLOWERS ©David B. Fankhauser, Ph.D., Professor of Biology and Chemistry University of Cincinnati Clermont College, Batavia OH 45103
Blood Root, a more primitive plant	This page has been accessed  times since 7 April 2003. rvsd 31 March 2000, 4 April 03	Squirrel Corn and  Dutchman's Breeches, two advanced plants

A number of trends in the development of flower morphology can be noted since angiosperms appeared on earth.  The following table lists four major trends, and gives picture examples of each trait (all examples taken by DBF in SW Ohio.)

TRAIT	PRIMITIVE	ADVANCED
1. number of flower parts	many, indefinite parts	few parts, fixed numbers
Bloodroot has indeterminant number of petals and stamen Spring Cress has four petals and six stamen
2. relation of parts	separate	fused
Apple has five distinct petals Ground Cherry has five fused petals
3. symmetry of parts	radial	bilateral
Horse Nettle has radial symmetry Common Blue Violet has bilateral symmetry
4. location of ovary	superior	inferior
Bloodroot has a superior ovary  (positioned above the petals) Ground Ivy has an inferior ovary

Here are nine common families of plants with which students should be familiar.
 

Family		traits	examples	Page in Peterson's Fieldguide toWildflowers
White Trout Lily                White Trout Lily Snow Drops                  Yellow Trout Lily	Lily	parts in 3s: 3/6 petals, 6 stamen, 3 lobed stigma	lily, onion	xvi
Spring Cress                    Cut- Leafed Toothwort	Cruciferae	4 petals in a cross, 6 stamen (2 are shorter)	cabbage, mustard	xix
Apple                                Cherry	Rose	5 rounded petals, 5 sepals, indefinite number of stamen	berries, apple, cherry	xx
Sweet Pea	Legume	5 petals, 2 lower: 2 in keel, 2 wings, 1 upper banner	beans, peas	xx
Common Blue Violet          Smooth Yellow Violet	Violet	parts in 5s, lower petal wide, veined	pansy, violet	xxii
Pepper and Salt             Golden Alexanders	Umbelliferae	umbrella-shaped clusters, 5 petals	carrot, Queen Ann's Lace, poison hemlock	xxiii
Purple Dead Nettle       Ground Ivy	Labiatae	corolla, 2 flaring lips, upper has 2 lobes, lower three lobes	mints	xxv
Horse Nettle                     Virginia Ground Cherry	Solanaceae	parts in 5s, stamen and pistil united to form beak. forms berry w/ many seeds	Tomato, potato, egg plant	xxv
Dandelion                                Wingstem	Compositae	cluster of many florets, rays around central disk	largest family, daisy, zinnia, dandelion	xxviii

In comparison of Monocots and dicots in Campbell's 6th:
Summary table 721
Seed Structure 792
Seed Germination 794
Stem structure 733
 

page 721 in Campbell's 6th	MONOCOTS	DICOTS:
example:	corn (or wheat, above)	bean (or alfalfa, above)
seed leaves (792, 793 & 794)	one	two (here is a bean seedling)
vascular tissue distribution (733)	complex distribution	arranged in ring
leaf structure (721)	veins usually parallel	veins reticular
root structure	fibrous or diffuse	tap root
flower parts	multiples of three	parts in 4s or 5s