Question

Which plant bears petaloid bracts?
A)Bougainvillea
B)Cassia fistula
C)Mimosa pudica
D)Ricinus

Answer 1

Hint: In botany, a bract could be a modified or specialized leaf, especially one related to a plant organ like a flower, inflorescence axis or cone scale. Bracts are often (but not always) different from foliage leaves. They will be smaller, larger, or of a distinct color, shape, or texture.

Complete answer:
Bracts (hypsophylls ) are special leaves at whose axils the flowers are borne. They're not always present and, if a bract is found, the flower is named bracteate while, if it's absent as within the families Cruciferae and Boraginaceae, the flower is ebracteate.
Bracts may drop off early (deciduous) or they'll be persistent, When bracts are present, they serve for the protection of flower buds within the young stage. Morphologically, a bract could also be formed by the whole phyllopodium or part of it.
Some shoots show transitional forms between normal leaves and bracts . Additional bract-¬like small and thin structures are sometimes borne on the peduncle or the pedicel between the flower and therefore the bract. These are called bracteoles and are of the character of prophylls. Bracts and bracteoles may present various appearances a number of which are:

1.Leafy or Foliaceous Bract: Bracts resembling ordinary green foliage leaves is also seen within the china-rose and variety of other plants like Acalypha indica (Euphorbiaceae), Adhatoda zeylanica etc.

2.Petaloid Bract: Bracts sometimes become brightly coloured simulating petals and perform the identical function. These may easily be mistaken for petals. Examples are Bougainvillea spectabilis of Nyctaginaceae where three flowers cluster together and also the large bracts are conspicuously bright red or orange.


3.Spathe Bract: These are large, thick, boat-shaped bracts called spathes covering the entire or part of a spadix inflorescence. These are often very large as seen within the inflorescence.
In some palms the spathe is the maximum amount as twenty feet long. It's seen in many other plants like arum, maize , banana ,etc. Spathes also occur in other varieties of inflorescences, e.g., the spike of Polyanthes.

4.Involucral Bract: In an inflorescence of the capitulum type found within the asterid dicot family, whorls of green sepaloid bracts occur round the base of the inflorescence. These form an involucre. Sometimes bases of those bracts fuse forming a cup-shaped structure. Such an involucre of bracts is additionally seen within the family Umbelliferae where, as in carrot (Daucus carota), the inflorescence could be a compound umbel and there's an involucre at the bottom of the full inflorescence.


5.Scaly Bract: Each individual floret of a capitulum often possesses its own scaly braci different from the involucral bracts. Scaly bracts also are seen interspersed between the florets of catkin and cyathium inflorescences.
In the strobile inflorescence of hop (Humulus lupulus ) which is employed within the manufacture of beer, each flower is born within the axil of a stiff, scaly, persistent bract.


6.Cupule: The acorn of oak and similar fruits of birch (Betula) and hazel (Corylus ), etc., of Cupulifereae possess a variety of hard and woody bracts or bracteoles at the bottom of the flower somewhat like an involucre. When fruit matures, these bracts fuse together forming a cup-shaped structure called cupule.


7.Epicalyx: In the Malvaceae, as in china-rose, a whorl of sepaloid green bracteoles occur just under the calyx and is named the epicalyx.
Such an epicalyx is additionally seen below the calyx of the strawberry (Fragaria of Rosaceae). An epicalyx is typically called an involucres due to the apparent resemblance.

8.Glume: Each spikelet of the family Gramineae bears as its base two scaly bracts called glumes or empty glumes.

9.Lemma and Palea: Each flower in a very spikelet of Gramineae bears a bract called lemma or the lemma which is usually awned at the tip, and a bracteole called palea which inserts within the lemma.

Hence, the correct answer is option (A)

Note: Bracts sometimes become brightly coloured simulating petals and perform the identical function of Cornaceae where the conspicuously bracts forming a whorl surrounding the cluster of small flowers within the centre, exactly appear as if a whorl of petals.
When a flower arises within the axil of a leaf-like structure, this structure is thought as a bract. Because bracts are large and brightly coloured structures, they're often mistaken for petals. This helps to draw in insects for pollination.