Classification of Flowers

·         Flowers are classified in various groups based on different criteria

§  Based on presence of male, or female or both reproductive structures

§  Perfect/Bisexual/Hermaphrodite Flower

·         These flowers bear both male and female reproductive structures

§  Imperfect/Unisexual Flower

·         Bears male or female reproductive structures

·         Staminate flower (male flower)

·         Pistillate/carpellate flower (female flower)

§  Based on presence or absence of any structure

§  Complete Flower

·         Flowers bear sepals, petals, pistils, and stamens

§  Incomplete Flowers

·         Sepals, petals, pistils, or stamen is missing

§  Based on the number of flowers

§  Simple flowers

·         One flower on an axis (receptacle)

§  Compound flowers or Inflorescence

·         Have more than one flower on the receptacle or axis

·         The axis forms the rachis and florets are attached on pedicels

§  Inflorescence are subsequently classified based on pattern of arrangement into;

·         Single inflorescence –same pattern of arrangement of florets

·         Compound inflorescence –complex pattern

·         Main inflorescences include;

o   Raceme (or racemose)

o   Spadix

o   Spike

o   Corymb

o   Umbel

o   Head

§  Based on flora variations

§  Flowers are grouped according to the placement of floral parts on the receptacle into;

·         Hypogynous flowers

o   Sepals, petals, and stamens are attached to a convex or conical receptacle at the base of the ovary

o   The ovary is called superior and the perianth is inferior or hypogynous

·         Perigynous flowers

o   Sepals, petals, and sometimes stamens borne on the edge or margin of the receptacle and appear to form a cup around the pistil

·         Epigynous flowers

o   Sepals, petals, and stamens appear to arise from the top of the ovary

o   The ovary is inferior and the perianth is superior or epigynous

§  Based on floral symmetry

§  Regular or Actinomorphic flowers

·         Flowers divisible into symmetrical halves by more than one longitudinal plane through the axis

§  Irregular or Zygomorphic flowers

·         Flowers divisible only by a single plane into two mirror-image halves

§  Asymmetrical flowers

·         Flowers indivisible into identical or mirror-image halves on any plane

Pink Flowers Photograph

Trees and Evans (15th Edition) Pharmacognosy, W. B. Saunders

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