Labiatae

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Chapter: Pharmacognosy and Phytochemistry : Study of Different Families

A British systematic botanist J. Hutchinson published his work, The Families of Flowering Plants in 1926 on dicotyle-dons and in 1934 on monocotyledons. Hutchinson made it clear that the plants with sepals and petals are more primitive than the plants without petals and sepals on the assumption that free parts are more primitive than fused ones.


LABIATAE

 

Habit: These are herbs and undershrubs with square stems.

 

Leaves: These are simple, opposite or whorled, exstipu-late and have oil glands.

 

Flowers: This is a zygomorphic, bilabiate, hypogynous and bisexual.

 

Inflorescence: This is a verticillaster. It is often reduced to a true cyme, as in tulsi.

 

Calyx: The petals are (five in number), gamopetalous and bilabiate, i.e. two lipped. The aestivation is imbricate.

 

Androecium: The stamens are four and didynamous. Sometimes there are only two, as in sage. They are epipetalous.

 

Gynoecium: The carpels are (2) and syncarpous. The disc is prominent. The ovary is four-lobed and four-celled, with one ovule in each cell, ascending from the base of ovary. The style is gynobasic, i.e. it develops from the depressed centre of the lobed ovary. The stigma is bifid.

 

Fruit: This is a group of four nutlets, each with one seed. The seed has only scanty endosperm, or even none.

 

Floral formula: ·׀·H K(5) C(5) A4 G(2)

 


                                       Floral diagram of labiatae

Examples: Tulsi, mentha, etc.

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