Onagracea: Characters, Distribution and Affinities

In this article we will discuss about:- 1. Characters of Onagracea 2. Distribution of Onagracea 3. Economic Importance 4. Affinities.

Characters of Onagracea:

Plants herb, leaves exstipulate, flower tetramerous, epigynous; flowers having typically the numerical plan of 4 i.e., S₄ P₄ A₄₊₄ G_(4-6); inferior multiovulate ovary terminated by an hypanthium from whose rim emerge sepals, petals and stamens.

A. Vegetative characters:

Habit:

Mostly herbs (occasionally aquatic) rarely shrub (Fuchsia) or trees (Hauya).

Root:

Tap, deep and branched.

Stem:

Herbaceous rarely woody, branched, occurrence of raphides, interxylary phloem, large aerenchyma in aquatic species.

Leaf:

Alternate or opposite, simple, stipules none or present and caducous.

B. Floral characters:

Inflorescence:

Axillary, solitary, spicate, racemose.

Flower:

Hermaphrodite, actinomorphic, tetramerous, epigynous, complete, zygomorphic in Lopezia.

Calyx:

Sepals 4, rarely less or more, valvate forming the calyx tube being basally united and ultimately adnate to the receptacular cup (hypanthium), persistent sometimes.

Corolla:

Petals 4 usually, rarely less or more or rarely absent, free and imbricate and usually clawed.

Androecium:

Stamens as many as or twice the number of petals, then in two whorls; anthers bithecal, dehiscence longitudinal, sometimes anther lobes are divided transversely by false plates into two or more false lobes, pollen grains are large.

Gynoecium:

Carpels usually 4, rarely 2, 3 or 5-6 united into four celled inferior ovary, rarely ovary is semi-inferior; style one, simple, stigma capitate or rarely notched. Ovules usually several, sometimes few or one, anatropous, ascending, horizontal or descending, on axile placenta.

Fruit:

Various loculicidal capsule, berry, nut or drupe.

Seed:

Comose of glabrous, non-endospermic.

Pollination:

Entomophilous.

Floral formula:

Distribution of Onagracea:

Onagraceae or Evening Primose family of about 20 genera and 650 species of world-wide distribution especially in temperate regions.

Economic Importance of Onagracea:

1. Medicinal:

The leaves and bark of Fuchsia magellanica have a medicinal use.

2. Dye:

From the perianth of Fuchsia is extracted ‘fuchsine’ a red dye used as a staining reagent.

3. Ornamental:

The species of Clarkia, Fuchsia, Oenothera and Godetia are cultivated for their ornamental flowers. The flowers of Fuchsia resemble ornamental eardrops and are popularly called Lady’s eardrops.

Affinities of Onagracea:

The family Onagraceae was included within the Myrtiflorae (or Myrtales) by Bessey, Wettstein and Rendle. Hallier included it as one of the primitive genera in his Polygalines (an order be treated as derived from Linaceae), and Hutchinson included it within his Lythrales (an order considered to have been derived from the Caryophyllales).

The Onagraceae is closely related to the.Myrtaceae, Melastomaceae and Lythraceae.

The genus Trapa by recent studies of Maheshwari (1945) have short to be distinct and transferred to Trapaceae (Hydrocaryaceae).

Common plants of the family:

1. Ludwigia perennis – herb occurring in rice fields.

2. Jussieua repens – a commonly occurring plant of family.

3. Oenothera – with 200 species indigenous to S. America.