In this article we will discuss about:- 1. Characters of Nyctaginaceae 2. Distribution of Nyctaginaceae 3. Economic Importance 4. Affinities 5. Important Types.
Characters of Nyctaginaceae:
Flowers open in late afternoon; flowers mostly hermaphrodite rarely diclinous, actinomorphic, usually subtended by an involucre of separate or united brightly coloured bracts or sepaloid bracts that are often mistaken for sepals; petaloid perianth, tepals 5; stamens 1- ∝; carpel one.
A. Vegetative characters:
Herb, shrub or scandent or trees.
Tap root, branched.
Herbaceous or woody, erect or even climbing e.g. Bougainvillea.
Alternate or opposite, simple, those of each pair being often very unequal, exstipulate.
B. Floral characters:
Cymose, biparous with a tendency to monochasial development in the higher branches.
Perfect or diclinous as in Pisonia by suppression of stamens or pistil, hypogynous, actinomorphic, rarely zygomorphic in Anisomeris usually subtended by an involucre of 3 to 5 separate or united brightly coloured bracts that are often mistaken for sepals.
In Mirabilis, each flower is surrounded at the base by an involucre of five sepal-like bracts; in Bougainvillea, there are three involucral bracts each subtending a flower, in Boerhaavia and others, the involucral leaves are reduced to teeth or scales.
Tepals 4-5, gamophyllous, tubular with wide spreading lobes, often petaloid (infundibuliform) imbricate or twisted, contorted, connate in a funnel shaped or tubular perigone, the base of which persists and enclosing the fruit forming the so called anthocarp.
Stamens variable 2 to 20, free, usually 5 to 8 or equal to number of petals but there may be fewer or more; filaments of unequal lengths.
One carpel, superior, unilocular with a single basal ovule; style long, simple.
Dry, one-seeded anthocarp (achene surrounded by persistent perianth lobes) indehiscent.
Distribution of Nyctaginaceae:
Nyctaginaceae or Four O’clock family includes 30 genera and 300 species according to Rendle. It is widely distributed in tropical and temperate America and warmer parts of the world. They are called four o’clock because of the fact that flowers in certain members of the group (Mirabilis) open in greatest numbers in late afternoon.
Economic Importance of Nyctaginaceae:
Boerhaavia diffusa’s root is laxative and also used in asthma, anemia, jaundice. It is an antidote to snake venom, B. repens is diuretic. The roots of Mirabilis jalapa are purgative. The leaves lessen inflammation and are applied to boils.
Mirabilis jalapa, Bougainvillea, Abronia. Pisonia aculeata is a hedge plant.
Affinities of Nyctaginaceae:
The family is closely allied to Polygonaceae. Bentham and Hooker placed it together with Amaranthaceae, Chenopodiaceae. Nyctaginaceae can be distinguished from Polygonaceae by the nature of its fruit enclosed in the persistent base of the perianth.
Common plants of the family:
1. Mirabilis jalapa – Four O’clock plant H. Gul-e-bas – ornamental plant.
2. Boerhaavia diffusa – Common weed after rainy season, medicinal.
3. Bougainvillea glabra, B. spectabilis ornamental with magneta bract.
4. Oxybaphus – Greek oxybaphus – a saucer.
5. Pisonia aculeata – a large climber, armed with recurved axillary spines.
Important Types of Nyctaginaceae:
1. Mirabilis jalapa (Four O’clock plant) (Vera. Gulabbas) (Fig. 89.1):
Large perennial herbs.
Tap and branched.
Erect, aerial, herbaceous or somewhat woody, branched, cylindrical, pinkish green, swollen nodes.
Cauline and ramal, opposite, petiolate, simple, entire, exstipulate, ovate, acute, glabrous, net veined, opposite leaves of pair unequal in size.
Cymose, dichasial cyme with a tendency to become monochasial cyme in higher branches.
Pedicellate, bracteate, an involucre of 5 sepaloid bracts, hermaphrodite, actionomorphic, complete, red, yellow or white, hypogynous. In Mirabilis, the flowers are arranged in cymes of three, of which only the middle flower develops; there remains an involucre of five parts at its base, which really belongs to cyme, but looks exactly like the calyx of the flower.
5 tepals, petaloid, imbricate or twisted, contorted, connate in a funnel shaped or tubular perigone, the base of which persists and enclosing the fruit forming the anthocarp.
5 stamens, alternate to tepals, filaments unequal, anther dithecous, basifixed, introrse.
Single carpel, ovary free, superior, unilocular, basal placentation, single basal erect ovule.
An achene, enclosed within the persistent perianth, indehiscent.
2. Boerhaavia diffusa (H. Sata) (Fig.-89.2):
Habit – Annual herb. Root – Fusiform.
Stem – A glabrous, prostrate or ascending and diffusely branched.
Simple, opposite, unequal, exstipulate, petiolate, ovate with rounded or cordate base, margin entire, apex obtuse, dorsal surface green, lower surface usually silvery white.
Small, bracteate, subsessile, actinomorphic, hermaphrodite, hypogynous.
Tepals 5, gamophyllous, pink.
Stamens 1-3 slightly exserted, filaments of unequal length.
Monocarpellary, unilocular superior, simple basal ovule, style simple.