Inflorescence Types,cymose and racemose types,examples with Diagrams

Different types of Inflorescence, Cymose and Racemose Inflorescence, compound types, Compound Inflorescence , Capitulum inflorescence , Spikelet Inflorescence , Spike inflorescence

1. Unit – II : Inflorescence – Cymose and Racemose Presented by Debanjan pandit, faculty of Raidighi college

2. Why This Portion is Important ?? Comparatively easy to score area. This portion contains 2-3 Questions per year. Straight forward questions. Tricks to remember all things. Inflorescence means the arrangement of the flower or flowers on the floral axis of a plant.

3. Racemose Type :The main axis grows indefinitely giving rise to younger flowers in an acropetal and centripetal order. ( oldest flower towards base, and younger flower towards apex) Cymose Type : The apical bud is a flower. The younger flowers are borne below it, in a basipetal and centrifugal manner. (oldest flower towards apex, and younger flower towards base) Types of Inflorescence

4. Raceme : The main axis has indefinite growth , where more or less equally pedicellate flowers are bourne , e,g ., Brassica nigra ( Brassicaceae )

5.   Corymb : Raceme, in which all the flowers reach the same level due to more elongation of the pedicel of older flowers, e.g., cherry Prunus cerasus

6. Umbel : When pedicellate flowers arise from a common point as in members of Umbelliferae or Apiaceae . ( Coriandrum sativum )

7. Spike: A raceme with sessile flowers, e.g., Adhatoda vasica , Callistemon , etc.

8. Spikelet: Small spikes arranged in a spike, raceme or panicle manner. Each flower consists of an awned bract, three stamens and an ovary with two feathery stigmas, e.g., Triticum aestivum .

9.   Spadix: Spike with a fleshy axis, enclosed by one or more large bracts called spathes, e.g., Colocasia ,Musa, Pistia , etc

10. Catkin: Pendant spike with unisexual flowers, e.g., Acalyphya hispida , Morus alba, Salix

11. Strobile : Modified spike where the pistillate flowers are borne singly in the axile of persistent membranous bract e.g., Humulus lupulus

12. Capitulum or Head: When numerous, small, sessile flowers are aggregated to form a dense inflorescence as in members of Compositae or Asteraceae . E.g., Helianthus annuus

13. Capitate : A dense cluster of sessile flowers arise upon a compressed rachis. e,g ., Mimosa pudica

14. Compound Raceme or Panicle: In this case the raceme is branched, and the branches bear flowers in a racemose manner, e.g., Delonix regia , Azadirachta indica , Clematis buchaniana , Cassia fistula, etc.

15.  Compound Corymb: Also known as corymb of corymbs. Here the main axis (peduncle) branches in a corymbose manner and each branch bears flowers arranged in corymbs. Typical example-cauliflower( Brassica oleracea var. botrytis ).

16. Compound Umbel: Also known as umbel of umbels. Here the peduncle (main axis) is short and bears many branches which arise in an umbellate cluster. Each such branch bears a group of flowers in an umbellate manner. Usually a whorl of leafy bracts is found at the base of branches and also at the bases of flowers arranged in umbellate way. The former whorl of bracts is called involucre and the latter involucel. Typical examples of compound umbel are— Daucus carota (carrot), Foeniculum vulgare (fennel), Coriandrum sativum (coriander),

17. Compound Spike: Also known as spike of spikelets.Branches of the main axis bear spike inflorescence. e.g., Amaranthus viridis , Amaranthus spinosus

18. Amaranthus spinosus

19. Compound Spadix: Also known as spadix of spadices. Here the main axis (peduncle) remains branched in a racemose manner and each branch bears sessile and unisexual flowers. The whole branched structure remains covered by a single spathe. The examples are common in Palmaceae ( Palmae ) family. cocos nucifera

20. Compound Head: Also known as head of heads or capitulum of capitula . In this case many small heads form a large head. The typical example is globe thistle ( Echinops ). In this plant the heads are small and one-flowered and are arranged together forming a big compound head.