Biology · Morphology of Flowering Plants · NEET
Perianth is a single word for the outer whorls of a flower when the calyx and corolla are not distinct (they look the same in colour and shape). Instead of naming an outer green whorl (calyx) and an inner coloured whorl (corolla) separately, we call the combined outer part the perianth. NCERT says: in flowers like lily, the calyx and corolla are not distinct and are termed perianth. This matters for NEET because floral formula questions use the symbol P (for perianth) instead of K and C.
In a normal flower you can clearly see two different whorls: the calyx (sepals, usually green, outermost) and the corolla (petals, usually coloured). When these two whorls are alike and you cannot separate sepals from petals, you stop using the words calyx and corolla and use one word, perianth. So calyx + corolla are for distinct whorls; perianth is for indistinct (similar looking) whorls. Rose has calyx and corolla; lily has a perianth.
Tepal is the name for a single unit of the perianth. Just as one unit of the calyx is a sepal and one unit of the corolla is a petal, one unit of the perianth is a tepal. A lily flower has 6 tepals arranged in two whorls of three. NEET often tests this: if calyx and corolla are not distinct, the parts are tepals, not sepals or petals.
Members of family Liliaceae show a perianth, for example lily, onion, garlic, tulip, Colchicum, Asphodelus and Gloriosa. These are mostly monocots. In their floral formula the perianth is written as P with the number of tepals (for Liliaceae, P3+3, meaning six tepals in two whorls of three that are often fused).
No. Perianth is an accessory (non-reproductive) part, exactly like calyx and corolla. The reproductive whorls are the androecium (stamens) and gynoecium (carpels). Perianth only replaces the accessory whorls when sepals and petals cannot be told apart; it does not include stamens or carpels.
When stamens are fixed onto the perianth (as in lily), they are called epiphyllous, sometimes written epitepalous. This is different from epipetalous, where stamens are attached to petals (as in brinjal). NEET links these terms, so remember: petals to epipetalous, perianth/tepals to epiphyllous (lily).
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Perianth is the outer, non-reproductive part of a flower used when the calyx and corolla cannot be distinguished, as in lily.
A tepal is a single unit of the perianth, used when a part cannot be called clearly a sepal or a petal. Lily has 6 tepals.
Lily is the standard NCERT example. Other Liliaceae members like onion, garlic and tulip also have a perianth.
The letter P is used for perianth. Calyx uses K and corolla uses C, but when they are not distinct, only P is written (e.g., Liliaceae P3+3).
They are called epiphyllous (epitepalous) stamens, as seen in lily. When stamens are attached to petals instead, they are epipetalous.
