The different between Apocynaceae and Acanthaceae:
1. Systematic position: This family belongs to subclass gamopetalae of Dicotyeldonae and order gentiales.
2. Distribution : There are 1400 species under 300 genera most abundant in tropics and subtropical area.
3. Habit : Shrubs or herbs with latex rarely trees.
4. Stem : Herbaceous woody or climbing and lianas.
5. Leaf : Simple opposite or whorled exstipulate. No cystolith in leaf.
6. Inflorescence : Cymose, sometimes corymbose or umbellate.
7. Flower: Regular bisexual actinomorphic, hypogynous often with corona.
8. Calys: Sepals five, fused but terminally free, imbricate, with glands.
9. Corolla: petals five gamopetalous sometimes tubular or funnel shaped twisted estivation.
10. Androecium: Stamens 4-5 epipetalous free, filaments united anthers sagitate usually connate at base of stigma ring like glandular disc present below.
11. Gynoecium: Carpels two free below and united by styles only or incompletely united .
1. Systematic position: This family belongs to gamopetalae of order personales.
2. Distribution: There are 2200 species under 240 genera widely distributed in tropics and subtropics.
3. Habit : Mostly herbs or shrubs few are climbers without latex. Some are xerophytes.
4. Stem : Herbaceous or woody not climbing.
5. Leaf : Simple,opposite exitpulate with cystolith, latex absent.
6. Inflorescence : Usually dischasilcyme, receme or spike bracteoles enclose the flower often perdorm the function of calyx.
7. Flower: Small regular zygomorphic bisexual, hypogynous, without coron.
8. Calys: Sepals 1-5 free gamosepalous imbricate or valvate.
9. Corolla: Bilipped sub-equally five lobed imbricate or controted.
10. Androecium: Stamens four, in two sets didynamous rarely five epipetalous one anther lobe.
11. Gynoecium: Bicarpellary synearpous 2-many ovules in axile placentation stigma bitid syle simple linear.