Essays - by Stephen G. Saupe, Ph.D.; Biology Department, College of St. Benedict/St. John's University, Collegeville, MN 56321; ssaupe@csbsju.edu; http://www.employees.csbsju.edu/ssaupe/ |
Plant Families for Gardeners
(prepared for a presentation at the Minnesota Master Gardener Conference, Summer 2004)
Plant Families � What and Why?
The family is the basic unit of classification used by taxonomists. A
family consists of a group of related genera that share a characteristic set
of features. Learning family characteristics is useful because: (a) family
naming/taxonomy is relatively stable; (b) it applies to any flora; (c) there
are a manageable number to learn; about 400 for flowering plants vs. 250,000
species); (d) an unknown species is relatively easy to identify once its
family is known. According the International Code of Botanical
Nomenclature, family names end in �-aceae.�
20 Common Plant Families:
APIACEAE
� Carrot Family
Herbs, hollow and furrowed
stems, leaves compound or dissected with sheathing leaf base; flowers
5-merous, often white or yellow; inflorescence an umbel (compound); style
swollen over ovary (stylopodium); ovary inferior, fruit a schizocarp.
Carrots, celery, dill, parsley
APOCYNACEAE (or ASCLEPIADACEAE)
� Dogbane or Milkweed Family
Herbs and shrubs, leaves
opposite or whorled, milky sap; flowers 5-merous; many with a corona (with a
hood and horn); anthers fused to gynoecium (gynostegium); pollen in pollinia
connected by two arms (translators) to a central body (corpusculum);
gynoecium bicarpellate, fused at apex; fruit a follicle, seeds comose.
VInca, milkweed.
ASTERACEAE
� Sunflower Family
Herbs (our species) with
flowers inserted on a receptacle surrounded by bracts (head inflorescence);
flowers may be regular (disk) or irregular (ray or ligulate); calyx reduced
to pappus; stamens 5, anthers connate; ovary inferior, fruit an achene.
Many species.
BORAGINACEAE
� Borage Family
Herbs, often hairy or bristly;
leaves alternate, stem round; ovary bicarpellate, 4-lobed, style gynobasic;
fruit of 4 nutlets, inflorescence cymose (scorpiod or helicoid). Bluebells,
comfrey, forget-me-nots
BRASSICACEAE
� Mustard Family
Herbs, acrid taste (glucosinolates);
flowers 4-merous; petals cruciform, often clawed; stamens tetradynamous (4
long, 2 short); fruit with a false septum, siliques and silicles.
Horseradish, broccoli, cabbage
CAPRIFOLIACEAE
� Honeysuckle Family
Shrubs; opposite leaves, no
stipules, ovary inferior, syncarpous, 2-8 carpels, fruit a berry (or
drupe). Honeysuckle, viburnum, elderberry, bush honeysuckle
CARYOPHYLLACEAE
� Pink Family
Herbs, swollen nodes, opposite
leaves joined by a transverse line, flowers 5-merous, petals notched at end;
gynoecium 2-5 carpels, free central placentation; fruit a capsule, opening
by teeth or valves. Carnations, pinks
CUCURBITACEAE
� Gourd Family
Vines, prostrate or climbing;
leaves palmately-lobed or compound, tendrils; stems often 5-angled,
bicollateral vascular bundles; flowers imperfect, often yellow or white;
stamens highly modified, usually 5, connate; gynoecium 3-carpelled,
syncarpous; placentation parietal; fruit a berry or pepo; rich in bitter
tasting tetracyclic triterpenoids and alkaloids. Pumpkins, melons, gourds
EUPHORBIACEAE
� Spurge Family
Herbs (ours); milky sap;
flowers highly reduced; staminate flowers a single stamen; pistillate
flowers a single pistil, tricarpellate, syncarpous; flowers borne in
cup-like structure (cyathium) often with glands on margin; colorful bracts
may subtend inflorescence; fruit a schizocarpic capsule.
Snow-on-the-mountain
FABACEAE
� Legume or Bean Family
There are three distinctive groups
or subfamilies of legumes. The only common one in Minnesota is the
Papillionoideae and is described here: Herbs, shrubs or trees, flowers
zygomorphic; corolla papilionaceous (uppermost banner, two lateral wings,
two fused keel petals); unicarpellate; fruit a legume. Many species.
GRASS-LIKE PLANTS (Poaceae � Grasses; Cyperaceae � Sedges; Juncaceae � Rushes)
IRIDACEAE
� Iris Family
Herbs, equitant leaves;
petaloid perianth, hypanthium often present; stamens three; inflorescence
subtended by a bracts, ovary inferior, tricarpellate, syncarpous. Iris,
blue-eyed grass
LAMIACEAE
� Mint Family
Herbs and shrubs, square stems,
often aromatic; leaves opposite; flowers 5-merous, irregular, bilabiate;
stamens 2 or 4, epipetalous, ovary 4-lobed, style gynobasic, fruit 4 nutlets.
Rosemary, sage, thyme
LILIACEAE
� Lily Family
Although this family is now
broken up into smaller ones, the following is a good unifying description:
Herbs, perennial from bulbs, corms rhizome or tubers; leaves linear with
parallel veination; flowers regular; perianth 3-merous, 6 tepals; gynoecium
tricarpellate, syncarpous, ovary superior. Lilies, tulips
MALVACEAE
� Mallow or Cotton Family
Herbs, often with mucilaginous
sap; leaves stipulate, palmately veined and lobed; epicalyx often present;
corolla 5 petals; stamens numerous, monadelphous, epipetalous; fruit a
capsule, seeds comose. Hollyhocks
ONAGRACEAE
� Evening Primrose Family
Herbs; 4-merous; hypanthium;
flowers often yellow; gynoecium syncarpous, four carpels, four stigmas;
pollen with plugs, viscin threads; ovary inferior. Evening primroses
ORCHIDACEAE
� Orchid Family
Herbs, perennial, leaves often
coriaceous and two-ranked; flowers highly irregular, 3-merous; lower petal
modified into a lip (labellum), twists 180 degrees during development;
pollen aggregated into a waxy mass (pollinia); androecium and gynoecium
fused into a column; ovary inferior, numerous tiny seeds.
RANUNCULACEAE
� Buttercup Family
Herbs; leaves compound or
dissected, often with sheathing base, no stipules; stamens numerous; carpels
numerous, apocarpous. Buttercups, wild columbine, hepatica, meadow rue,
delphinium.
ROSACEAE
� Rose Family
Herbs, shrubs or trees; leaves
stipulate, often serrate, flowers 5-merous; hypanthium, stamens numerous,
fruits variable (achenes, follicles, drupes, pomes). Variable family,
includes strawberry, stone fruits, apples, spiraea,
SCROPHULARIACEAE
� Figwort Family
Herbs (and shrubs); flowers
irregular, bilabiate, 5-merous; stamens 4 (or 5), epipetalous, didynamous (2
long, 2 short), a fifth stamen often present as a staminode; gynoecium
syncarpous, bicarpellate, ovary 2 locules, placentation axile; ovary
superior. Foxglove, penstemon, mullein
SOLANACEAE
� Tomato Family
Herbs, alternate leaves;
bicollateral vascular bundles; flowers actinomorphic; calyx 5-merous, often
persistent in the fruit; corolla 5-merous, various but may be plicate;
androecium 5 stamens, epipetalous; gynoecium bicarpellate, syncarpous; fruit
a berry or capsule; rich in alkaloids. Eggplant, tomato, potato, pepper
References:
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