Inflorescence of Flower

It is the mode of arrangement of flower in a group in a specialized branch called peduncle. It consists of inflorescence axis and mother axis. Peduncles are of two types- receptacle and scape.

Different types of inflorescence that are observed are:

1. Racemose inflorescence - It is of two types.

Simple racemose inflorescence:

Typical Raceme - Unbranched, elongated peduncle bearing pedicellate or stalked flowers acropetally. Example - Delphinium, Linaria etc.

Corymb  - All the acropetally arranged flowers come to lie at the same level due to slight shortening or elongation of peduncles of lower flowers. Example- candytuft.

Corymbose raceme  - Like a corymb near the growing point and raceme lower down though the peduncles of the lower flower are longer. Example - mustard.

Umbel  - Pedicellate flowersarranged centripetally around an extremely reduced peduncle with an involucre below. Example - Brahmi booti, hydrocotyle.

Spike - Sessile flowers borne acropetally over an elongated peduncle. Example –bottle brush, Amaranthus.

Spikelets - It is a compact spike having a few flowers born on axis called rachilla and surrounded by two scales called glumes. Example- wheat, oat, grass etc.

Strobile - It is a spike in which the flowers develop in the axils of persistent membranous bracts. Example- Hop.

Catkin - Compact unisexual spike often hanging. Example-Mulberry, Willow,Birch.

Spadix - It is a modification of catkin in which the peduncle is fleshy and thick with upper part sterile and lower part bearing one or both the types of unisexual flowers surrounded by a large bract called spathe. Example-In maize the female flower develops in a spadix.

Capitulum - Peduncle is flattened to form receptacle that bears the centripetally arranged Sessile flowers or florets surrounded by involucre of bracts. Example- Cosmos, Zinnia, Chrysanthemum etc.

Compound racemose inflorescence:

Raceme of racemes  - Racemes are born acropetally on a raceme. Example - yucca, Asparagus etc.

Corymb of corymbs – An axis bearinga number of corymbs in a corymbose fashion. Example - Cauliflower, Pyrus.

Umbel of umbels - Many umbels develops from a common point in an umbellate fashion. Example - coriander, carrot, cumin.

Spike of spikes  - Example - Amaranthas

Spike of spikelets  - Example - Wheat.

Spadix of spadices - Example – Date pulm, Coconut.

Capitulum of capitula - Echinops.

2. Cymose Inflorescence:

Uniparous – Example – Begonia, Drosera.

Biparous – Example - Dianthus, Nyctanthes.

Multiparous –Calotropis, Hamelia.

Cymose head – Kadam, Acacia.

Scapigerous – Onion.

3. Mixed inflorescence - They are of different types –

Thyrsus – Cymose  cluster arranged acropetally. Example - grape vine.

Mixed spadix  – Spadices have cymose inflorescence arranged acropetally on fleshy axis. Example - Banana.

Panicle of spikelets – Spikelets arranged in a compound raceme. Example- oat, rice.

Corymb of capitula – Example- Ageratum.

Other types – Like umbel of capitula, cyme of umbels . Example- Lantana.

Special inflorescence: - They are of four types:

Hypanthodium – It is flask shaped fleshy (male flowers),a pore or ostiole lined by scales and a short canal bearing hair. Example- peepal, banyan.

Coenanthium – Saucer shaped receptacle with upturn margin bearing florets. Example-Dorstenia .

Verticillaster – It is raceme of verticles or whorls of flowers born in the axile of opposite leaves . Example- Ocimum, salvia.

Cyanthium – Consists of involucre of 5 fused bracts that encloses a central achlamydeous  pedicellate tricarpellary,syncarpous female. Example-Euphorbia.

Eleventh Grade

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