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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.



Habit: These are shrubs and trees (rarely herbs).


Leaves: The leaves are simple or compound, alternate or rarely opposite and gland dotted.


Flowers: These are regular, bisexual and hypogynous. The disc below the ovary is prominent and ring or cap like.


Calyx: There are four or five sepals free or connate below and imbricate.


Corolla: Petals four or five, free, imbricate.


Androecium: The number of stamens varies, they can be as many, or more often twice, as many, as the petals (obdiplostemonous), or numerous, as in citrus and aegle. They are free or united in irregular bundles (polyadel-phous), and inserted on the disc.


Gynoecium: There are generally (4) or (5) carpels, or ∞, as in citrus. They are syncarpous or free at the base and united above, and either sessile or seated on the disc. The ovary is generally four- or five-locular, or multilocular as in citrus, with axile placentation (parietal in limonia only). There are usually 2-∞ (rarely 1) ovules in each loculus, arranged in two rows.


Fruit: This is a berry, capsule or hesperidium.


Seeds: The seeds may or may not have an endosperm. Polyembryony is frequent in Citrus, e.g. lemon and orange (but not pummelo and citron)


Floral formula: H K 4–5 C 4–5 A 8, 10 or ∞ G (4, 5 or ∞)


                                   Floral diagram of Rubiaceae

Examples: Citrus limon, Citrus aurentium, Aegle marmelos (wood apple).


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