Introduction to inflorescence - class-XI

On the basis of fowers and inflorescence the most advanced family in angiosperms is Asteraceae. Asteraceae are mostly herbaceous plants, but some shrubs, trees and climbers do exist. Asteraceae are generally easy to distinguish from other plants, mainly because of their characteristic inflorescence and other shared characteristics. The Asteraceae commonly referred to as or sunflower family are an exceedingly large and widespread family of Angiospermae. The name Asteraceae comes from Aster, the most prominent genus in the family, that means star, and is connected with its inflorescence star form. As for the term Compositae, more ancient but still valid, it obviously makes reference to the fact that the family is one of the few angiosperm ones to have composite flowers. This family has a remarkable ecological and economical importance. The Asteraceae may represent as much as 10% of autochthonous flora in many regions of the world. Most members of Asteraceae are herbaceous,but a significant number are also shrubs, vines, or trees. The family has a  worldwide distribution and is most common in the arid and semiarid regions of subtropical and lower temperate latitudes. The Asteraceae are an economically important family.

A family which was named after its inflorescence is Apiaceae (umbelliferae). The defining characteristic of this family is the inflorescence: a simple or compound umbel. Flowers across the Apiaceae are fairly uniform and are usually perfect hermaphroditic and actinomorphic, but some are andromonoecious, polygamomonoecious, or even dioecious, with a distinct calyx and corolla, but the calyx if often highly reduced, to the point of being undetectable in many species, while the corolla can be white, yellow, pink or purple. The flowers are nearly perfectly entamerous, with 5 petals, sepals, and stamens. The androecium contains of 5 stamens, but there is often variation in the functionality of the stamens even within a single inflorescence. Some flowers are functionally staminate while others are functionally pistillate.

Anthodium inflorescence is characteristic of sunflower. Sunflower belongs to Asteraceae.The genus is one of many in the Asteraceae that are known as sunflowers. It is distinguished technically by the fact that the ray flowers, when present, are sterile, and by the presence on the disk flowers of a pappus that is of two awn-like scales that are cauducous. They bear one or
several to many wide, terminal capitula (flower heads), with bright yellow ray florets at the outside and yellow or maroon disc florets inside. Several
ornamental cultivars have red-colored ray florets. Indeterminate simple inflorescences are generally called as racemose anthodium inflorescence. The main kind of racemose inflorescence is the raceme  and the other kind of racemose inflorescences can all be derived from this one by dilation, compression, swelling or reduction of the different axes.

The peduncle is compressed to a flattened or convex disc, the receptacle and the flowers (florets) are sessile this represents capitulum inflorescence. A flower head or capitulum is a very contracted raceme in which the single sessile flowers share are borne on an enlarged stem. Capitulum can be used as an exact synonym for pseudanthium and flower head, however its use is generally but not always restricted to the Asteraceae family. At least one source defines it as a small flower head. Flower head is a special type of inflorescence  in which anything from a small cluster to hundreds or sometimes thousands of flowers are grouped together to form a single flower-like structure. Pseudanthia take various forms. The individual flowers of a pseudanthium commonly are called as florets.

An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Determinate simple inflorescences are generally called as cymose. The main kind of cymose inflorescence is the cyme. The cyme is refered as dichasial when there are two secondary axis. If in an inflorescence two lateral branches develop on either side of the terminal lower which again branch is known as dichasial cyme. Dianthus  species are mostly herbaceous perennials  and some are low subshrubs with oody basal stems. The leaves are opposite, simple, mostly linear and often strongly glaucous grey-green to blue-green. The flowers have five petals, with dichasial cyme.

Depending upon the mode of branching of peduncle, the inflorescences are of two main types - Recaulescent and Concaulescent.
When the bract is attached to the stem holding the flower (the pedicel or
peduncle), it is said to be recaulescent; sometimes these bracts or bracteolesare highly modified and appear to be appendages of the flower calyx. 
Recaulescences is the fusion of the subtending leaf with the stem holding the bud or the bud itself, thus the leaf or bract is adnate to the stem of flower. When the formation of the bud is shifted up the stem distinctly above the subtending leaf, it is described as concaulescent.

Unisexual flowers are present in Morus, Ficus and Poinsettia. A unisexual flower is one that has stamens but no pistils or having pistils but no stamens. A flower having only stamens is said to be staminate, or male. A flower having only pistils is said to be pistillate, or female. In many unisexual flowers, the nonfunctioning organs of the other sex are present in reduced form, thus attesting to the plants original bisexual nature. Such flowers are said to be functionally male or functionally female.

• The stalk holding the complete inflorescence and bearing the flowers or fruit, in a flowering plant is known as the peduncle. 
• The pedicle is the stem that attaches a single flower. 
• The petiole is the stalk that attaches a leaf to the stem and the leaflet of a pinnately compound leaf is called pinna. 

The arrangement of flowers is known as the inflorescence. It is useful for the plant as it increases the chances of attracting insect pollinators such as bees that help in pollination. The flower morphology, size, colour, nectar and odour act as signals for attracting these pollinators. 

Multiple fruits also called as collective fruits, are fruits that are formed from a cluster of flowers called inflorescence. Each flower in the inflorescence produces a fruit, but these mature into a single mass. An multiple fruit is a fruit that develops from the merger of several ovaries that were separate in a single flower. Not all flowers with multiple ovaries form aggregate fruit; the ovaries of some flowers do not become tightly joined together to make a larger fruit. 

Multiple fruits, also called as collective fruits, are fruits that are formed from a cluster of flowers called as an inflorescence. Each flower in the inflorescence produces a fruit, but these mature into a single mass. An multiple fruit is a fruit that develops from the merger of several ovaries that were separate in a single flower. In contrast, a simple fruit develops from one ovary. Not all flowers with multiple ovaries form aggregate fruit; the ovaries of some flowers do not become tightly joined together to make a larger fruit. 
Thus, the  statement of reason is correct but the assertion statement is in correct.
Therefore, the correct answer is option E.

Inflorescence and fruit of sunflower is capitulum and cypsella. The main feature of the family is the composite flower type in the form of capitula surrounded by involucral bracts.The individual flowers in a head have 5 fused petals, but instead of sepals, have threadlike hairy or bristly structures called as pappus, which surround the fruit and can stick to animal fur or be lifted by wind, aiding in seed dispersal. The whitish fluffy head of a dandelion commonly blown on by children, is made of the pappus, with tiny seeds attached at the ends, whereby the pappus provides a parachute like structure to help the seed be carried away in the wind.
Therefore, the correct answer is option C.

Inflorescence is collection of flowers. An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Inflorescence can also be defined as the reproductive portion of a plant that bears a cluster of flowers in a specific pattern.
Therefore, the correct answer is option C.

Composite fruits or multiple fruits that are developed from entire inflorescence and are of two types:-

Inflorescence is the arrangement of flowers on the stem of a plant. It provides the chance of cross-pollination. It makes flowers more conspicuous to attract insects towards it. Large inflorescence enhances the chance of wind pollution. Insects are the pollinators. Due to the aroma emitted from the petals and the nectar glands and colour of the flower insects get attracted towards the flower. When an insect grazes through a flower to collect nectar, pollen grains stick on its body from the anther. As the insect move to each flower, it leaves a residue of pollen on the stigma and triggers the process of pollination. Some of these pollinators are honeybees, bumblebees butterflies etc.

When  a fruit is formed from  the entire inflorescence like in pineapple, jackfruit etc it is a composite fruit

Cyathium inflorescence is seen in Euphorbia splendens and Euphorbia pulcherrima (Poinsettia). In cyathium inflorescence, the bracts become fused to form a cup-shaped structure. This cup completely encloses a single female flower surrounded by a large number of male flowers. The cyathium is surrounded by brightly coloured bracts.

Composite fruits : These fruits are developed from the complete inflorescence and are known as incandescence.
These are of 2 types ..
(1) Sorosis                      

All the florets are disc florets in vernonia. The name of an exceedingly large and wide spread family of flowering plants.

The flowers of Cassia fistula are grouped in the axillary and many-flowered racemes. These inflorescences are large in size and up to 15-40 cm long, pendulous and bright yellow. Long inflorescence of Cassia fistula from Sri Lanka and reaching up to 238 cm. It can be considered as the longest recorded legume inflorescence.

So the correct option is B.

A thyrse/thyrsus is a type of inflorescence in which the main axis grows indeterminately and the subares (branches) have determinate growth. Inflorescence is thyrse/ thyrsus in Grape.

A) Cyathium is the special inflorescence in which the single female flower is present in the center and is surrounded by a number of male flowers inside a cup-shaped involucre.

(A) Pedicel - Stalk of the flower

1. Rhipidium is scorpioid cyme having all flowers in one plane.Ex. Solanum nigrum
2. In helicoid cyme, the flowers are born on one side. Ex Begonia
3. Capitulum also called Racemose head in which peduncle is flattened that form receptacle that holds centripetally arranged sessile flowers or floret surrounded by an involucre of bracts. Ex Sunflower Helianthus annuu.
4. In multiparous cyme, the main branch converts into flower the old flower at the center and younger at the periphery while it produces lateral branch as well. Ex Calatropis.

A catkin is a slim, cylindrical cluster of flowers with no petals, usually wind-pollinated and sometimes insect pollinated. The female flowers in catkin are sessile and solitary in the axilla of a bractea longer than themselves. In spike, flowers are bisexual, sessile or non- pedicellate. In spikelet, flowers are hermaphrodite. In raceme, flowers are pedicellate an bisexual.

Hemicyclic flowers are flowers having floral leaves partly in spiral and partly in whorl. 

1. The type of inflorescence in which flowers are protected by enveloping bracts known as a spathe. ex:-banana.
2. The flowers are protected by spathe but the axis is branched. ex: palm and coconut.
3. The axis is branched and the flowers are born sessile on the branches. ex: wheat.
4. When the main axis is branched and flowers are arranged in a corymbose manner. ex:-cauliflower

The inflorescence in the Bougainvillea flower is a simple cyme or cymule. In the cymule, the peduncle ends in a flower and only 2 lateral branches. These are produced which also ends in flowers. Thus, 3 flowered inflorescences will be formed. Flowers are arranged in a basipetal manner. Since the inflorescence number will be given here 34. Thus, the total numbers of flowers would be $34 \times 3 = 102.$

Single female flower-like inflorescence of the Euphorbiaceae i.e. Poinsettia is called a cyathium. The single female flower of cyathium has 3 carpels syncarpous pistil. Also, the inflorescence number given here is 42. Thus hence the number of female flowers is 42.

So, the correct answer will be 102,42.

The correct option is C.

(a) In the racemose type of inflorescence, the youngest flower is borne near the apex and the oldest is borne at the base of the inflorescence. This is called the acropetal order. Basipetal order is seen in the cymose inflorescence.