In this article we will discuss about:- 1. Characters of Primulaceae 2. Distribution of Primulaceae 3. Economic Importance 4. Affinities 5. Important Types.
Characters of Primulaceae:
Herbaceous habit, gamopetalous corolla, single whorl of stamens opposite the corolla lobes; unilocular ovary with free-central placentation; fruit dehiscent capsule, seeds numerous and endospermic.
A. Vegetative characters:
Habit:
Perennial or annual herbs.
Root:
Tap or adventitious.
Stem:
Corms, tuber or rhizome, in aerial stem internodes suppressed, so the leaves are radical in dense clusters.
Leaf:
Simple, exstipulate, alternate, opposite or whorled, sometimes radical frequently glandular; pinnately dissected in the aquatic-Hottonia.
B. Floral character:
Inflorescence:
Umbellate, racemose or spicate or solitary.
Flower:
Actinomorphic, very seldom zygomorphic, hermaphrodite, pentamerous, bracteate, hypogynous or very rarely semiepigynous.
Calyx:
Sepcels 5, rarely 4-9 lobed gamosepalous, foliaceous, persistent, imbricate.
Corolla:
Petals 5 rarely 4 or more than 5; gamopetalous, 5 pentite, tubular or rotate, funnel shaped or companulate, imbricate or contorted.
Androecium:
Stamens 5 rarely 4 or more than 5, inserted in corolla tube and opposite to corolla lobes, (obdipolstemonous); filament usually short, free, anthers bithecous, introrse.
Gynoecium:
Carpels 5, syncarpous, ovary superior, very varely half inferior, unilocular, free-central placentation; ovules many amphitropious to semi-anatropous, bitegmic, style long or short, stigma entire, minute.
Fruit:
Capsule dehiscing transversely.
Seed:
Small endosperm abundant fleshy or horny.
Pollination:
Entomphilous.
Floral formula:
Distribution of Primulaceae:
Primrose family comprises of 28 genera and 800 species distributed mostly in the temperate and mountainous region of the northern hemisphere, many are artic and alpine.
Economic Importance of Primulaceae:
Economic importance of the family is practically none. Ornamentals-Anagallis arvensis, Centunculus tenullus, Primula sinensis etc. are cultivated as garden ornamentals.
1. Dye:
Lysimachla vulgaris is a used as febrifuge and yields a yellow dye.
2. Poisonous:
Large tubers of Cyclamen europeum are poisonous if taken uncooked.
Affinities of Primulaceae:
Primulaceae resembles Caryophyllaceaw in having same type of gynoecium and free-central placentation. As concluded by Douglas (1936) (and in essence by Dickson (1936) reduced flower of the Phimulaceae has descended from an ancestor which was characterised by a plurilocular ovary and axile placentation. This primitive flower might well be found in centrospermal stock, as Wernham, Bessey and Hutchinson, have suggested.
Common plants of the family:
1. Anagalis arvensis – Annuel herb with gland dotted leaves and true flowers.
2. Centunculus tenellus – very small annual.
3. Primula umbellans – herb with small red or white flowers.
Division of the family & chief genera:
Tribe I: Primuleae:
Ovary superior, capsule with valvular dehiscence. Genera. Primula, Androsace. etc.
Tribe II: Cyclamineae:
Ovary superior, capsule valvular. Petals inflexed. Plants with corm. Genus: Cyclomen only.
Tribe III: Lysimachieae:
Fruit and ovary as above but capsule with circumssile dehiscence; corolla lobes contorted Genera, Lysimachia, Trientalis etc.
Tribe IV: Samoleae:
Ovary semi-inferior, Genus: Samolus only.
Table V: Corideae:
Flowers Zygomorphic; calyx spiny. Genus: Coris.
Important Type of Primulaceae:
Anagallis arvensis (Fig. 71.1):
Habit:
An annual, glabrous procombent herb.
Root:
Tap root.
Stem:
Hebaceous branching from base.
Leaf:
Ovate or lanceolate, acute, opposite, sessile, gland-dotted.
Inflorecence:
Solitary axillary, erect.
Flower:
Bracteate, actinomorphic, hermaphrodite, hypogynous, pentamerous, blue.
Calyx:
Sepals 5, gamosepalous, narrowly lanceolate, acuminate, inferior.
Corolla:
Petals 5, gampetalous, rotate, inferior, blue.
Androecium:
Stamens 5, polyandous epipetalous, obdipolostemonous, inferior.
Gynoecium:
Carpels 5, syncarpous, ovary superior unilocalar, free central placentation with many ovules.
Fruit:
A capsule.
Seed:
Minute, many and endospermic.
Floral formula:
