HOW TO USE THIS GUIDE

The primary question to ask when examining a plant species is: Is this a relatively primitive or relatively advanced species or does it fall somewhere in the middle of the evolutionary continuum?

Take a series of steps: (a more detailed clarification and helpful hints for each step is provided below).

1. DETERMINE THE FLORAL FORMULA:

Count the number of petals, sepals, stamens, and styles. You will be particularly interested in the number of stamens compared to the number of petals.

2. FIND THE CORRECT MASTER TABLE.

Determine if the unknown species is a Gymnosperm or Angionsperm and within Angiosperms, whether it is a Dicot, Monocot, or water plant with indistinguishable flowers.

3. FIND THE CORRECT ROW.

Using the overall shape of the flower, decide on the appropriate subclass. More particularly, find the type of flower within the subclasses listed. This gives you the appropriate row of the table.

4. FIND THE CORRECT COLUMN.

Determine the number of stamens compared to the number of petals and then choose the appropriate column. (The unisexual condition, such as monoecious or dioecious flowers, takes precedence over comparision of number of stamens to number of petals, because if the unknown species happens to be female, where there are no stamens, such a comparison cannot be made.)

5. FIND THE CORRECT CELL.

The combination of the column and row gives the appropriate table cell with its corresponding section number.

6. FIND THE PLANT FAMILY.

Go to the appropriate section (subclass/petals vs. stamens section), and find the appropriate family from the section table. The list of families is grouped by whether the species are herbs, shrubs, or trees. Furthermore, the entries are grouped by the number of styles (the family formulas are grouped by the number of styles) and then using the entire formula to choose the appropriate family. Helpful hints to family identification are provided below the floral formulas.

The rows of the table give the section numbers and then families by the number of styles, while the columns providives information on the types of leaves.

7. Within the main body of the text, go to the appropriate family table in the list of plant species by class, subclass, family, genus, and species.

As with any guide, the more familiar one becomes with the scheme, the more one can skip steps in this process. With increased plant knowledge, a field botanist can go straight to the family, genus, or even the species (using the index or table of contents).

DETAILED CLARIFICATION OF THE STEPS, AND AN EXAMPLE:

STEP 1. DETERMINE THE FLORAL FORMULA

A helpful hint is that when you cannot decide whether you are seeing petals or sepals, it is best to assume that you are looking at sepals. (Of course, in the case of the Magnolia Subclass you may be looking at tepals.)

To take an example, for multiflora rose (Rosa multiflora), the floral formula is 5 5 10 1.

STEP 2. GYMNOSPERM OR ANGIOSPERM (DICOT OR MONOCOT)

  leaves needle or scale like lvs not needle or scale like: mostly without parallel veination parallel veination
usually dioecious: females in pine type cones, and males in much smaller conical structures Gymnosperms    
floral parts * mostly; not in 3's or 6's; floral formula example:          5 5 10 1   Angiosperms (Dicots)  
floral parts in 3's or 6's; floral formula example: 3 3 6 1     Angiosperms (Monocots)

* = number of petals, sepals, and stamens

To take an example: multiflora rose is an Angiosperm and a dicot because the flower parts are not in sets of 3 and the non-needled leaves are not parallel veined.

STEP 3. FIND THE CORRECT ROW (i.e., the subclass)

DICOTS: 6 SUBCLASSES AND THE ASTER FAMILY

  PETALS SEPALS STAMENS STYLES LEAVES
MAGNOLIA          
group A no petals petal-like numerous separate whorled
group B tepals tepals numerous separate whorled
WITCH-HAZEL (many with indistinguishable pets or lack pets) no petals 4-5 4-5 one alt/opp
PINK          
group A no petals petal-like   fused alternate
group B 5 petals 2,5,(5) 5, 4-N (2-8) opp/whorled
DILL partial fusion; either pets or seps, but not both, fused (mustards 4 pets in form of cross; others us. w 5 petals) 4 or 5 seps centrifugal; (fused in mallow family) 1 or seldom 3-4 styles  
ROSE (separate, very distinct petals) us. 5 (exc. the order Myrtales) none fused centripetal; us. 5 or 10, exc. Myrtales often one us. alt.
ASTER (us. with fused parts) us. 4 or 5 and fused 4 or 5; some fused never numerous; us. 4 or 5 two fused; some w/ inferior ovaries many opposite

MONOCOTS: 4 SUBCLASSES

  Petals Sepals Stamens Styles
ARROWHEAD 3 or 0 3 or 0 some have many separate; often more than 3
AROIDS spadix (spike) spathe (hood) 6 (2-3)
SPIDERWORT 3 or 0; perianth is.. . ...well-developed or reduced 6 is highest fused; highest nunmber is 3
LILY 3 or 6 3; petal-like us. 3 or 6 3 fused

For example: since multiflora rose has very distinct and separate, regular petals, it is in the rose subclass, regular petals. That means it is in row V.2.

HELPFUL SHORTCUTS FOR FLOWER IDENTIFICATION:

FINDING THE CORRECT SUBCLASS (FAMILY SOMETIMES) GIVEN A SPECIFIC FLOWER TYPE

flower shape scientific name subclass family, genus
back-spur   Dill Violaceae (violet)
ball on a stalk above bracts   Rose Euphorbiaceae (spurge)
bell-shaped campanulate Aster Campanulaceae (bell), Polemoniaceae (phlox), Hydrophyllacea (waterleaf)
bowl-shaped   Mag Magnoliaceae (magnolia), Ranunculaceae (buttercup), Papaveraceae (poppy)
bracts, prominent with cups   Rose Euphorbiaceae (spurge)
bracts, prominent with cuplike circles, green   Pink Nyctaginaceae, Mirabilis
greenish, fuzzy-looking   Pink Amaranthaceae (amaranthus)
showy, white   Rose Cornaceae (dogwood)
catkins   Witch oaks, hickories, birches, and many others
cattails   Spiderwort Typhaceae (cattails)
clover-like flwr heads   Rose Fabaceae (pea), Polygalaceae (milkwort)
coil, rolled-up   Aster Boraginaceae (borage)
cross-shaped cruciate Dill Brassicaceae (mustard)
cup-shaped cupulate Mag Magnoliaceae (magnolia), Liriodendron; Rose Santalaceae (sandalwood), Comandra
cups under flowers (see bracts)      
curved flower sprays   Aster Boraginaceae (borage)
daisy-like   Aster Asteraceae (aster)
falls and standards   Lily Iridaceae (iris)
heart-shaped   Mag Fumariaceae (fumitory)
helmet-like galeate Aster Scrophulariaceae (snapdragon) Castilleja
hibiscus-like flowers   Dill Malvaceae (mallow)
hood and spike   Arum Araceae (aroid)
hyacinth-like flower   Lily Pontederiaceae (pickerelweed)
indistinguishable   Pink various pink subclass flowers
indistinguishable   Witch Urticaceae (nettles)
irregular flower (2 lateral petals)   Lily Orchidaceae (orchids)
lantern-like, japanese lantern   Dill Ericaceae (heath)
lily-like   Lily Liliaceae (lily)
lipped, two upper arched personate Aster Scrophulariaceae (snapdragon)
lipped, two bilabiate Aster Lamiaceae (mint)
morning-glory like   Aster Covolvulaceae( morning glory), Solanaceae, Jimsonweed
notched petals   Pink Caryophyllaceae (pink)
pants-shape   Mag Fumariaceae (fumitory), Dutchman's breeches
pea-shaped papiloneaceous Rose Fabaceae (pea)
pincushion, egg-shaped w/ spines amid florets   Aster Dipsacaceae (teasel)
pipe, smoking   Mag Aristolochaceae (birthwort)
pouched flowers   Lily Orchidaceae (orchid)
protruberance on the top   Aster Lamiaceae (mint) skullcaps and basil
ribbon   Witch Hamamelidaceae (witch hazel)
rose-like (separate pets)   Rose Rosaceae (rose)
round ball (globular, petalless)   Spiderwort Sparganiaceae (burreed)
saucer-shaped rotate   many
slipper shaped calceolate Lily Orchidaceae (orchid)
snap-dragon like   Aster Scrophulariaceae (snapdragon)
spathe and spadix   Arum Araceae (aroid)
spherical subglobose Aster  
spurred   Aster Balsaminaceae (touch-me-not)
strap-shaped ligulate Aster Asteraceae (aster)
swollen, one side gibbous Aster Scrophulariaceae (snapdragon)
swollen ventricose Aster Scrophulariaceae (snapdragon): Penstemon
thistle-like   Aster Dipsacaceae (teasel)
tooth-like   Aster Asclepiadaceae (milkweed)
tubular throat & limb only slghtly wider   Aster  
tubular, elongate funnelform Aster Convolvulaceae (morning glory)
tubular, flared salverform Aster  
tubular, showy   Aster Bignoniaceae (catalpa), Valerianaceae (valelrian)
umbels of small white flowers   Aster Apiaceae (parsley)
urn-shaped urceolate Aster & Dill Ericaceae (heath)
wheel-shaped rotate   many
wind sock   Rose Balsaminaceae (touch-me-not)
pistil      
cross shaped stigma   Rose Onagraceae (evening primrose)
forked style   Aster Scrophulariacese (snapdragon)
single pistil (4 or 5 united petals)   Dill Ericaceae (heath)
single pistil (5 5 5 1 floral formula)   Aster Boraginaceae (borage)
style forked   Aster Scrophulariaceae (snapdragon)
thickened head and short beak   Dill Violaceae (violet)
vase-like and sits admid numerous stamens   Dill Clusiaceae (St. Johnswort)
stamens      
curved anthers   Rose Melastomaceae (meadow beauty), Scroph. (blue curls)
location (ea stamen at center of a petal instead of betwn petals)   Dill Primulaceae (primrose)
location, 4-12 stamens joined to 4-12 petals   Aster Gentianaceae (gentian)
protruding stamens   Dill/Aster Capers/Lamiaceae (mint)
protruding stamens (long, drooping)     Polemoniaceae, Polemonium
protruding stamens and style   Aster Valerianaceae (valerian)
unequal lengths   Aster Verbenaceae (vervain), Scrophulariaceae (snapdragon)
united on central pistil   Dill Malvaceae (mallow)
united to form beak   Dill Primulaceae (primrose), Dodecatheon (shooting star)
united with pistil to form beak   Aster Solanaceae (nightshade)

STEP 4: FIND THE CORRECT COLUMN: WHAT IS THE NUMBER OF STAMENS COMPARED TO THE NUMBER OF PETALS?

The values of this variable are in evoltuionary order from most primitive to most advanced. For instance, within the dicots, N (or numerous) stamens is more often associated with primitive plants whereas the condition of having fewer stamens than petals is associated with the most advanced dicot families.

N stamens = numerous stamens

N or > = numerous stamens or the number of stamens is greater than the number of petals, but not twice as many

2x = the number of stamens is twice the number of petals

1x = the number of stamens is equal to the number of petals

fewer = the number of stamens is fewer than the number of petals

For example, multiflora rose has numerous stamens, so the correct column is the third one, numerous stamens.

STEP 5: FIND THE CORRECT CELL: WHAT IS THE APPROPRIATE SECTION NUMBER?

The intersection of the selected row and column gives the appropriate table cell, which in turn gives the section numbers. The tables give more information than just the family. You can often identify the genus or in some cases even the species via the table.

For example: for multiflora rose, the correct section number is V.2.4, for Rose subclass (separate petals) separate regular petals, 2x stamens.  

STEP 6: FIND THE PLANT FAMILY

Given the appropriate section table, find the family.  The columns contain information on the type of leaves and these can be used to double check the accuracy of the family identification. If the leaf type of the unknown plant species does not match the leaf types of the family, a wrong identification has been made. The rows give the floral formula. The table cells give the number of the plant family along with the page number from Gleason and Cronquist (1991). The actual detailed family identification tables for dicots and monocots provide much more information than necessary. For instance, many of the genera or actual species are listed, where the mere listing of the family would be surricient, but, again, this serves as an accuracy quick-check for those using the tables.

For example: Going to the Dicot family tables, one finds section number V.2.3. This is divided into herbs, vines, shrubs, and trees. Since multiflora rose is a shrub, we begin the search for the floral formula within this grouping. Matching the floral formula to the ones listed in section V.2.3 under shrubs, we see that a match is found for the rose family (Rosaceae). We can double check our identification by noting if the type of leaves for our species matches the type of leaves for the genera of the family selected. Multiflora rose has alternate divided leaves and the genus of rose has alternate divided leaves.

STEP 7: FIND THE CORRECT FAMILY: GO TO THE APPROPRIATE FAMILY TABLE WITH ITS ASSOCIATED GENERA

The appropriate place is usually the family, but in some cases could be the genus, or even the species.

For example: going to page 238 in the Gleason and Cronquist book (1991) leads us to the rose family table of genera. Or you can go directly to the twentieth genus (rose) in the rose family. From the genus table, one finds the species identification for multiflora rose.