Classification of Angiosperms

Angiosperms are classified into two classes based on cotyledons present in seeds.

1. Monocotyledons

• The seeds contain a single cotyledon.
• This group has adventitious roots only. Roots contain 8 to 20 vascular bundles. In a stem, vascular bundles are scattered.
• Secondary growth is absent because vascular bundles of stems lack cambium.
• The leaves are isobilateral, simple, usually linear, and contain parallel venation.
• Each flowers whorl is usually trimerous or has three members.
• Usually, calyx and corolla are undifferentiated. The perianth is present instead of them,
• Usually, they are pollinated by wind.
• Generally, fruits are trilocular.
• Examples: sugarcane, banana, lilies, etc. 

2. Dicotyledons

• The seeds of dicotyledons contain two cotyledons.
• Usually, they have tap roots, but in some cases, adventitious roots are also present.
• The root contains 2 to 6 vascular bundles.
• Stems vascular bundles are arranged in a ring.
• Secondary growth is possible because of cambium present in vascular bundles of stems.
• The leaves are dorso-ventrally flattened, depict, and have reticulate venation.
• Flowers are usually tetramerous or pentamerous. 
• Usually, calyx and corolla are distinct.
• They usually are pollinated by insects.
• Fruits are usually pentalocular.
• Examples: grapes, sunflowers, tomatoes, etc.