The Ericaceae

"Heath Family"


Ericaceae	Leucothoe fontanesiana (Switch ivy)

The Iridaceae family is comprised of 99 genera made up of 2,245 different species. Gladiolus, the major genus of the family is made up of 180-300 species and the Moraea genus has 100-111 species. These plants have a cosmopolitan distribution, with diversity centers in the Eastern Mediterranean region, tropical America, and South Africa. In the United States and Canada there are 28 genera with 109 species, the largest being Iris and Sisyrinchium. The Texas flora includes 6 genera and 26 species with a single endemic species.

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

Vegetative Characters

perennial herbs
often with rhizomes, bulbs, or corms
leaves simple, entire, alternate and basal
leaves parellel-veined, numerous, usually narrow, with open basal sheath
inflourescence determinate, cymose and often appearing racemose or paniculate
flowers actinomorphic or zygomorphic, perfect, epiginous, usually large and showy
flowers individually or collectively subtended by 1 or 2 extended bract(s) (see picture below) forming a spathe
perianth of 6 tepals, distinct or usually basally connate and forming a tube
Floral structure:

gynoecium, especially the styles, often petaloid or otherwise modified in interesting ways

Reproductive Characters

androecium of 3 stamens, opposite and often adnate to the outer tepals.
filiaments distinct or sometimes basally connate and forming a tube.
gynoecium of 1 pistil, 3-carpellate.
inferior ovary, 3-locular, axial placentation, 1 style, 3 stigmas, terminal.
ovulaes few to many in each locule
fruit is a loculicidal capsule with numberous seeds
fleshy endosperm, small linear embryo

Diagnostic Characters

perennial herbs with rhizomes, bulbs, or corms
3-merous flowers with petaloid perianth and 3 stamens
loculicidal capsule
saponins and various terpenoid compounds usually present
tissues with tannins and calcium oxalate crystals.
mucilage ducts

Economic Importance/Fun Facts

saffron dye and spice is made from the stigmas of Crocus sativus.
orris root (fragrant substance) is used in perfumes and cosmetics and is found in the rhizomes of Iris spp.
Crocus, Dietes, Eustylis, freesia, gladiolus, iris, ixia (corn-lily), moraea (butterfly-iris, Natal-lily) , neomarica (fan-iris) , sisyrinchium (blue-eyed grass), and Tigrida (tiger-flower) are all commonly used as ornamentals.
the flowers are usually pollinated by insects seeking the nectar in the base of the floral tube.
Insects pollinating the Iris flower use the large tepal as a landing platform, transferring pollen from the previous flower to the stigma and is dusted with the new pollen from the anther while reaching for the nectar. Upon exiting the tube it brushes up against the nonreceptive surface of the stigma, protecting the plant from self-pollination.

Evolutionary Adaptations and Relationships

generally it is aggreed upon by botanists that the Iridaceae are related to the Liliaceae, and allied families.
the family is divided into sub-families, tribes, and genera based on the rootstock (rhizomes, bulbs, or corms), inflourescence type, floral symetry, and style morphology.
cladistic analysis based on morphology support the monophyly of Iridaceae
the phylogenic position of Iridaceae is uncertain; morphological characters place it with liliales, rbcl sequences place it within Asparagales
based on a combination of morphology and chloroplast DNA the Iridaceae are considered a basal group of the Asparagales order

Glossary of Terms

Cosmopolitan: Widely distributed over the world.
Cymose: A usually broad and flattish determinate inflorescence, i.e., with its central or terminal flowers blooming earliest.
Bract: A more or less modified leaf subtending a flower or belonging to an inflorescence.
Spathe: A sheathing bract or pair of bracts partly enclosing an inflorescence.
Tepal: A division of the perianth--a sepal or a petal--of a flower in which the calyx and corolla are almost identical in appearances.
Loculicidal: Longitudinally dehiscent between the partitions of the locule.
-merous: A suffix preceded by an Arabic number or numeric prefix such as tri-, indicating how many of each part a flower possesses; 5-merous would be a flower with 5 sepals, 5 petals, etc., while trimerous would have three of each part.
Saponin: A glycoside compound of plants which has a foaming or soap-like action.
Tannin (syn. tannic acid): Any of various soluble astringent complex phenolic substances of plant origin, possibly giving protection to the plants. Tannins are used especially in tanning, dyeing, and making inks and pharmaceuticals.

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.csdl.tamu.edu/FLORA/Wilson/tfp/lil/iripage2.htm
http://glossary.gardenweb.com/glossary
http://www.botany.hawaii.edu/faculty/carr/irid.htm
http://www.csdl.tamu.edu/FLORA/imaxxiri.htm
http://hcs.osu.edu/hcs300/iris.htm

Pictures


Iridaceae bract and ovary	Herbertia lahue


Alophia drummondii	Sisyrinchium sp.

More information on the Iridaceae

For questions or feedback, contact: Kelly McKay