“A racemose inflorescence is one in which the main axis does not terminate in a flower, but continues to grow indefinitely.”

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This is why it is commonly referred to as an indefinite or indeterminate inflorescence.

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[What is Inflorescence?](#What is Inflorescence?)

Racemose Inflorescence

Types of Racemose Inflorescence

Characteristics and Examples of Different Racemose Inflorescences

Inflorescence is the arrangement of flowers on a plant. It is usually composed of a main stem with secondary branches bearing the flowers.

The apex of a plant produces different floral appendages at successive nodes. The arrangement of flowers on the floral axis is called an inflorescence. The inflorescence can be two types based on whether the apex continues to grow or not.

Types of Inflorescence

The flowers in Racemose are supported laterally and the main axis continues to grow in an acropetal succession.

Cymose - Here, the main axis of the flower terminates, resulting in limited growth.

Other Types of Inflorescence

The other special types of inflorescence are:

• Spadix
• Spike
• Capitulum
• Corymb
• Umbel
• Head

Compound Inflorescence - The main axis branches one or more times in a cymose or racemose fashion.

The Cyathium has a highly reduced inflorescence, with a cup-shaped involucre formed by the fusion of five bracts.

Hypanthodium - It is characterized by a flask-shaped receptacle that forms a hollow cavity, with terminal pores surrounded by scales.

Verticillaster - It is a special type of inflorescence seen in the family Lamiaceae. It is a condensed form of a dichasial cyme with sub-sessile or sessile flowers.

Racemose Inflorescence

The main characteristics of the racemose inflorescence are:

The growth of the main axis (peduncle) is never-ending and continues to produce a flower bud.

The flower rarely grows on the peduncle.

Peduncle is monopodial

The first formed flowers are formed at the base of the peduncle.

Flowers are borne in acropetal succession, with older flowers at the base and younger ones at the tip.

A group of flowers arranged centripetally has the younger flowers in the middle and the older flowers at the periphery.

Flowers do not protect newly formed fruits.

Grouping of flowers is not as common

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Types of Racemose Inflorescence

##Types of Racemose Inflorescence

A. Elongated main-axis: The different types of racemose inflorescence can be classified based on the branching pattern, length of peduncle, and presence or absence of pedicel (a small stalk that bears the flower).

1. Raceme

2. Spike

3. Spikelets

4. Catkin

5. Spadix

Shortened Main-Axis:

1. Corymb

2. Umbel

c. Flattened Main Axis:

1. Capitulum

See Also: Difference between Cymose and Racemose inflorescence

Characteristics and Examples of Different Racemose Inflorescences

• A racemose inflorescence is an arrangement of flowers in which the flowers are borne on a main axis, with the oldest flowers at the base and the youngest at the tip.
• Examples of racemose inflorescences include:
  • Spike: A spike inflorescence consists of a single main axis with flowers that are all of the same size and age, and that emerge directly from the stem. Examples include: foxglove, snapdragon, and larkspur.
  • Raceme: A raceme inflorescence consists of a single main axis with flowers that are of varying sizes and ages, and that are borne on short stalks (pedicels). Examples include: sweet pea, cosmos, and clematis.
  • Corymb: A corymb inflorescence consists of a single main axis with flowers that are of varying sizes and ages, but that all emerge from the same level of the stem. Examples include: daisy, aster, and yarrow.
  • Umbel: An umbel inflorescence consists of a single main axis with flowers that are of the same size and age, and that emerge from the stem at the same level. Examples include: carrot, parsley, and fennel.

A1. Raceme: The main axis is unbranched and elongated, with pedicellate flowers arranged in acropetal succession. The flowers at the base of the raceme have longer stalks than the younger flowers at the top.

• Examples:
  • Brassica campestris (mustard)
  • Raphanus sativus (radish)
  • Crotalaria retusa (rattleweed)
  • Cleome viscosa (Asian spiderflower)
  • Antirrhinum majus (snapdragon)
  • Convallaria majalis (lily of the valley)
  • etc.

A compound raceme or panicle is an inflorescence in which the main axis is branched and lateral branches bear flowers in a simple raceme manner.

Examples:

• Mangifera indica (mango)
• Azadirachta indica (neem)
• Delonix regia (Gulmohar), etc.

A2. Spike: The main axis is unbranched and has unlimited growth in the form of a raceme, but the flowers are sessile, meaning they are attached directly to the peduncle without a stalk.

Examples:

• Piper longum (long pepper)
• Acyranthes (chaff flower)
• Amaranthus (amaranth)
• Justicia adhatoda (Malabar nut)
• etc.

Compound spike, also known as the spike of spikelets, is a type of sessile flower (spikelets) found on a branched main-axis. Examples of this type of flower include wheat, barley, sorghum, oats, etc.

A3. Spikelets:

The Poaceae family (Graminae, Grass) is characterized by spikelets.

Individual flower units are called Spikelets

The central axis of the inflorescence is called a rachis

Spikelets have two scaly bracts present at the base called Glumes.

The number of florets per spikelet can differ between species.

Each floret has neither a calyx nor a corolla

The lemma is the larger, external bract that encloses the reproductive organs of the floret, while the smaller, internal bract is referred to as the palea.

Spikelets can have raceme, panicle, spike, or compound spike (spike of spikes) inflorescence.

Raceme Spikelet: Spikelets that are attached to a rachis (central axis) and are borne on pedicels can be seen in examples such as Festuca, Paspalum (crown grass), and Echinochloa (barnyard grass).

Panicle Spikelet: Spikelets are attached to panicle branches, rather than the rachis. Examples of plants with panicle spikelets include Avena, Switchgrass, Reed Canary Grass, and Alopecurus (Foxtails), among others.

Spikelet: Spikelets are small, flower-bearing units that are sessile and attached directly to the rachis or panicle branches (compound spike) without a pedicel. Examples include Hordeum, ryegrass, and Triticum aestivum (Wheat).

A4. Catkin: It is a modified spike with a drooping central axis, containing unisexual sessile flowers that are arranged closely on the peduncle. These flowers have inconspicuous petals and scaly bracts.

-Examples: -Morus alba (mulberry), -Betula (birches), -Qercus (oaks), -Salix (willows), etc.

A5. Spadix: A modified spike with a fleshy axis, the spadix contains numerous sessile flowers arranged acropetally. It is enclosed by a large, bright, colourful and curved bract known as a “spathe”. The female flowers are located at the base, with male and sterile flowers at the top. This structure is found in monocotyledons.

Examples: Present in the plants of family Araceae (arums), Musaceae, Palmaceae

In the compound spadix, the main axis is divided into several branches, each of which is topped with a sessile flower. The entire inflorescence is then enclosed by a single, thick, boat-shaped spathe. For example, the coconut plant has a compound spadix.

Examples:

• Caesalpinia (peacock flower)
• Iberis amara (candytuft)

Anthurium with Spadix

B1. Corymb: In this type of inflorescence, the peduncle is short and the flowers are attached to pedicels. All the flowers are at the same level, with the stalk of the lower flower being longer than the stalks of the upper flowers.

A compound corymb is when the main axis is branched in a corymbose manner and each branch has flowers arranged in corymbs.

Examples:

• Cauliflower

B2. Umbel: The main axis is shortened and is accompanied by an involucre of bracts (whorl). Flowers arise from the axil of bracts, each with a pedicel of the same length, spread from a common point. These can form a simple umbel or a compound umbel, also known as a “umbel of umbels”. This type of inflorescence is characteristic of the Apiaceae (Umbelliferae) family.

Examples:

• Centella asiatica (Brahmi)
• Allium cepa (onion)
• Fatsia japonica (paper plant)
• Primula veris (cowslip) etc.

Compound umbel:

• Coriandrum sativum (coriander)
• Foeniculum vulgare (fennel)
• Daucus carota (carrot)
• Conioselinum pacificum (parsley)
• etc.

C1. Capitulum (Head):

Capitulum, also known as a racemose head, is an advanced type of inflorescence. It is characteristic of the Asteraceae (Compositae) family. The peduncle is short, flattened and broad, and the flowers are referred to as “florets”.

Florets are sessile and arranged in a centripetal manner, with outer flowers being older and inner flowers being younger.

Individual florets are bracteate

The inflorescence is surrounded by one or more whorls of bracts (involucre)

Florets may be unisexual, bisexual, or sterile.

Ray florets and disc florets are two types of florets. Ray florets are strap-shaped while disc florets are central tubular.

If two types of florets are present in a capitulum, it is known as heterogamous.

If all the flowers of a capitulum are the same, it is known as homogamous.

• Examples:
  • Helianthus annuus (Sunflower)
  • Zinnia
  • Tagetes erecta (Marigold)
  • Cosmos
  • Mimosa pudica
  • Acacia
  • etc.

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Frequently Asked Questions

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Racemose inflorescence is a type of flower arrangement in which flowers are borne on an unbranched stem in a regular pattern. The flowers may be arranged in a single whorl or in several whorls.

Inflorescence is a type of arrangement of flowers in which the main axis does not terminate in a flower, but instead continues to grow, referred to as racemose inflorescence.

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Which plant has Racemose inflorescence?

Examples of plants with racemose inflorescence include mustard, snapdragon, gulmohar, wheat, barley, and parsley.

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I love to eat pizza

What is the difference between Racemose and Cymose?

Racemose inflorescence is a type of flowering pattern where flowers are borne on a single main axis, and the flowers are borne in an indeterminate number of branches. Cymose inflorescence is a type of flowering pattern where flowers are borne on a single main axis, but the flowers are borne in a determinate number of branches.

The main difference between racemose and cymose inflorescence is in the location of flowers on the main axis. In racemose type, flowers are borne laterally and the main floral axis shows indefinite growth, whereas in cymose type, flowers are borne apically and the main floral axis shows definite growth.

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I love to eat pizza

Yes, umbel is a type of racemose inflorescence.

Yes, umbel is a type of racemose inflorescence, wherein the main axis is shortened and each flower has a pedicel of the same length, radiating from a common point. Examples of plants with umbels include parsley, dill, coriander, fennel, onion, etc.

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Yes, Racemose is acropetal.

Yes, the arrangement of flowers is acropetal in racemose inflorescence, i.e. younger flowers or buds are present at the top and older flowers are present at the bottom. In a group of flowers, the arrangement is centripetal, i.e. younger flowers are present in the middle and the older flowers are present towards outside.

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