The Ericaceae

"Heath Family"


Ericaceae	Leucothoe fontanesiana (Switch ivy)

The Ericaceae family is comprised of 99 genera made up of 2,245 different species. Rhododendron, the major genus of the family is made up of 500-850 species and the Erica genus has 500-665 species. These plants have a widespread distribution on acidic soils throughout temperate zones, with diversity centers in southern Africa and western China. In the United States and Canada there are 44 genera with 219 species, the largest being Arctostaphylos and Vaccinium.

Click here for a distribution map of the Iridaceae in the U.S.A.

Vegetative Characters

small trees or shrubs
sometimes perennial herbs
leaves simple, entire to serrate with flat to recurved margins
leaves alternate and exstipulate
micorrhizal roots

Reproductive Characters

inflourescence indeterminate, racemose, paniculate, corymbose or fasciculate
flowers can also be solitary, axillary or terminal.
flowers actinomorphic or slightly zygomorphic, perfect, hypogenous to epiginous, generally showy
hypogenous or epigynous nectariferous disc
calyx usually synsepalous with 4-5 lobes, imbricate to valvate.
corolla usually sympettalous with 4-5 petals, urseolate, funnelform, or campanulate
androecium of 8-10 stamens with outer whorl opposite the petals. Filiaments usually distinct or sometimes flat, dilated or s-shaped.
dehiscing by pored or sometimes longitudinally (see picture)
gynoecium of 1 pistil, 4- to 5-carpellate.
inferior or superior ovary, 5-locular, axial placentation (see picture), 1 style and 1 stigma.
fruit is a loculicidal capsule, berry or drupe
Floral structure:

Diagnostic Characters

campanulate to urseolate corolla
8-10 stamens with outer whorl opposite the petals
single style inserted into depressed ovary apex

Economic Importance/Fun Facts

fruit from Vaccinium (blueberries and cranberries)
toxic resin in in many such as lambkill and lountain-laurel.
medicinal plants: labrador-tea, lemonleaf with oil of wintergreen
ornamentals

Evolutionary Adaptations and Relationships

according to recent studies (1993) the currently accepted five subfamilies may not all be monophyletic, and the hypothesis of many authors is that the Ericaceae, as defined here, may be paraphyletic.(Zomlefer)
some authors suggest the inclusion of the closely related Epacridaceae and Empetraceae in order to make the Ericaceae monophyletic.
stamen characters have been stressed as taxonomic indicators within the family.

Glossary of Terms

Racemose: Resembling a simple inflorescence of pediceled flowers upon a common more or less elongated axis.
Paniculate: Resembling a loose, irregularly compound inflorescence with pedicellate flowers
Corymbose: Resembling a flat-topped or convex open flower cluster, the outer flowers opening first. In the stricter use of the word, equivalent to a contracted raceme and progressing in its flowering from the margin inward.
Fasciculate: In close bundles or clusters.
Loculicidal: Longitudinally dehiscent between the partitions of the locule.

References and Links

Zomlefer, Wendy B., 1994. Guide to Flowering Plant Families. The University of North Carolina Press Chapel Hill, NC USA.
Judd, W. S., C. S. Campbell, E. A. Kellogg, P. S. Stevens. 1999. Plant Systematics: a phylogenetic approach. Sinauer Associates, Inc. Sunderland, MA U.S.A.
http://www.unibas.ch/botschoen/17/antoenien/x/104.jpg
http://glossary.gardenweb.com/glossary
http://www.botany.hawaii.edu/faculty/carr/erica.htm
http://www.biology.lsa.umich.edu/courses/bio215/ERICACEAE.jpg
http://www.library.utoronto.ca/polyclave/ericaceae/Ech15_16.gif
http://www.phy.duke.edu/~fortney/tours/dunedin/rhodedendron.jpg

Pictures


Ericaceae	Ericaceae pores


Rhodedendron	placentation

For questions or feedback, contact: Kelly McKay