calyx corolla perianth

1. FLORAL ORGANS

2. CALYX
• Calyx is the outermost floral whorl. It covers and protects the floral bud. It is
formed of green and leaf-like appendages, called sepals.
• In some plants, sepals are brightly coloured and scented, just like petals.
Then, they are called petalloid sepals (e.g., Mussaenda).
• In very few plants, sepals are reduced to a hairy structure, called pappus (e.g.
Tridax, Vernonia). It is an adaptation for the wind-dispersal of seeds.
• In balsams, one of the sepals may form a tubular structure, called spur. Calyx
with spur is called spurred calyx.

3. • If all the sepals are free and unfused, the calyx is called polysepalous (e.g.,
Annona). If the sepals fuse to form a cup, the calyx is called gamosepalous
or symsepalous (e.g., Hibiscus).
• Sepals are always sessile and generally have an entire margin. In some
cases, however, the margin of the sepals is uneven. Thus, in rose, the
margin is coarsely toothed.
• Calyx may be polysepalous or gamosepalous. In the former, sepals are
free from each other (e.g., Annona), whereas in the latter, sepals fuse to
form a cup (e.g., Hibiscus).

4. Modifications of calyx
• Calyx is variously modified in form and structure. Some common
modifications include spurred calyx, pappoid calyx, foliar calyx, spinous
calyx, hooded calyx, etc.
• (i) Spurred calyx - One or more sepals form a long, tubular and pointed
structure, called spur. e.g., balsams.
• (ii) Pappoid calyx - Sepals are modif to a hairy structure, called pappus
(e.g., Tridax, Vernonia). This is an adaptation for seed dispersal.
• (iii) Foliar calyx - Sepals are modified to form a leaf-like calyx.
• (iv) Spinous calyx - Sepals are modified into spines (e.g., water chestnut).
• (v) Hooded calyx - Sepals enlarge to form a hood-like structure.

5. • (vi) Tubular calyx - Sepals fuse to form a tube.
• (vii) Cupulate calyx - Sepals fuse to form a cup.
• (viii) Urceolate calyx - Sepals fuse to form an urn-shaped structure.
• (ix) Companulate calyx - Sepals fuse to form a bell-shaped structure.
• (x) Bilabiate calyx - Sepals fuse to form a two-lipped structure.
• (xi) Infundibuliform calyx - Sepals fuse to form a funnel-shaped structure.

7. Classification of calyx
(i) Caducous calyx - Sepals fall off pre-maturally soon after flower
opening. (e.g., Poppy)
(ii)Deciduous calyx - Sepals fall off together with petals soon after
fertilization. (e.g., Mustard)
(iii)Persistent calyx - Sepals do not fall off, but persist on the fruit (e.g.,
Solanum, Datura, brinjal).
(iv) Acrescent calyx - Sepals persist and calyx continues to grow as a loose
jacket around the fruit (e.g., Physalis, Withania).
(v) Marcescent calyx - A persistent calyx, wit a shrivelled and dried up
appearance (e.g., Guava).

8. Functions of the calyx
1. The main function of the calyx is to protect the delicate petals and the
essential organs.
2. When the sepals are green, the calyx performs photosynthesis to some
extent.
3. When the calyx is coloured, showy and petalloid, it helps in
pollination.
4. When the calyx is modified into pappus hairs, it helps seed dispersal
by wind.

9. Corolla
• Corolla constitutes the second set of floral organs.
• It is situated in between the calyx and the androecium and is
usually composed of a single whorl of petals.
• Petals are generally thin, delicate, brightly coloured and
sometimes sweet smelling. This makes the flowers conspicuous,
showy and attractive.
• In some flowers (e.g., Annona, Polyalthia), petals are thick,
succulent and green in colour. Such petals are said to be sepaloid.
• Just as sepals, petals may be either free from one another, or they
may be wholly or partially united. In the former, corolla is
polypetalous (e.g., Crotalaria), and in the latter, it is gamopetalous
(e.g., Ixora).

10. • In polypetalous corolla, petals are often provided with a small,
narrow, stalk-like lower portion, called claw, and an upper
expanded portion, the limb. Such petals are said to be clawed.
• In gamopetalous corolla, the lower portion is known as " tube",
and the upper portion, the “limb". The upper portion is often
lobed, the number of lobes indicating the number of petals
constituting the corolla.
• In some cases, corolla develops a number of outgrowths
appendages, which may be in the form of small lobes or long hairy
structures. Such appendages are called coronal outgrowths, and
they collectively form the corona. They add to the attraction of
corolla (e.g., Passiflora).
• In some plants, such as peas , corolla is butterfly-like. It is called
papilionaceous corolla.

11. • Corolla can be regular (actinomorphic) or irregular (zygomorphic).
• In the former petals are uniform in size and shape and are symmetrically
arranged (e.g., Hibiscus). But, in the latter, they are dissimilar in size and shape
and asymmetrical in arrangement (e.g., Pisum).

12. • Based on petals, several types of corolla can be recognized. Some of them are
the following.
• (i) Regular corolla - Petals are uniform in size and shape, and symmetrical in
arrangement.
• (ii) Irregular corolla - Petals are dissimilar in size and shape and
asymmetrical in arrangement.Flower 5960 Angiosperm Morphology
• (i) Polypetalous corolla - Petals are free and unfused (eg. Cuciferae)
• (iv) Gamopetalous corolla - Petals are fused (eg. Solanaceae)
• (v) Caducous corolla - Petals fall off soon atter fertilization.
• (vi) Deciduous corolla - Petals fall off after drying

13. • (vii) Persistent corolla - Petals do not fall off, but remain attached to the fruit.
• (viii) Cruciform corolla - Petals are arranged in a cross-like manner (eg.Brassica)
• (ix) Rosaceous corolla Petals are arranged concentrically as in rose flower.
• (x) Caryophyllaceous corolla - Petals with claws at right angles to limbs.
• (xi) Papilionaceous or zygomorphic corolla - Petals have butterfly-like appearance.
• (xii) Tubular corolla - Petals fuse to form a tube
• (xiii) Campanulate corolla - Petals fuse to form a bell-shaped structure
• (xiv) Hypocrateriform corolla - Gamopetalous corolla with tubular and narrow
basal portion, and bowl-like terminal portion.
• (xv) Infundibuliform corolla - Petals fuse to form a funnel-shaped structure.
• (xvi) Urceolate corolla - Petals fuse to form a structure with swollen middle and
tapering tip.
• (xvii) Rotate corolla - Petals fuse to form an apically saucer-shaped structure.
• (xviii) Bilabiate corolla - Petals fuse to form a double-lipped structure
• (xix) Ligulate corolla - Petals fuse to form a structure with tubular base and flap-
like tip.

16. Aestivation
Aestivation is the arrangement of sepals or petals in the bud condition in relation to
one another on the thalamus. The following types are more commonly met with in
flower:
1. Valvate: Adjacent petals or sepals are just in touch with one another without any
overlapping - e.g., Mimosa.
2. Valvate induplicate: The margins of petals are folded inwards-e.g., Datura
Ipomoea.
3. Contorted or twisted: Sepals or petals overlap regularly in such a manner, each
sepal or petal overlaps the next one and is overlapped by the previous one This may
result is in a twisted appearance, e.g., Allamada, Plumeria, Hibiscus
4. Imbricate: This is a type of aestivation in which one sepal or petal is completely
outside, another one is completely inside, and the remaining ones are partly inside
and partly outside. Imbricate aestivation is of two types, namely descendingly
imbricate and ascendingly imbricate. Descendingly imbricate or vexillary aestivation
is found in the papilionaceous corolla of Fabaceae. In it the posterior petal (standard
petal) is found completely outside and the anterior petal (one of the keel petals) is
completely inside. Ascendingly imbricate aestivation is found in the corolla of
Caesalpiniaceae, where the posterior petal is completely inside and the anterior petal
is completely outside.

17. 5. Quincuncial: Sepals or petals are arranged in five units two of which are
completely interior, two are completely exterior and the remaining one is
partially interior and partially exterior.
6. Induplicate-convolute: This type of aestivation is a combination of twisted
and induplicate types and is seen in the flowers of Convolvulus, Ipomoea, etc.
In this case, corolla is gamopetalous and regular and consists of a narrow,
tubular lower and a broad, spreading, and circular upper portion. In the upper
portion, there are five long, triangular, and outwardly radiating whitish
portions. At all these places, a corolla is very thick, while between them it is
thin and delicate. In the bud, all the thin portions are folded inwards and the
corolla is twisted in such a way that only the thickened portions are exposed.
This affords good protection to the bud.

18. Perianth
• In monocots, in general, and in a few dicot families in particular (those
belonging to Monochlamydae), flowers are monochlamydous due to the
presence of only one type of accessory whorl, called perianth.
• Its individual units are called tepals.
• It is neither true calyx nor true corolla. Perianth is protective and attractive.
• In some plants, perianth becomes brightly coloured and highly attractive.
Then it is called petalloid-perianth (e.g., Gloriosa,orchidaceae).
• In Graminae it is in the form of highly reduced, pinhead – sized and creamy
– white outgrowths, called lodicules.