Vastu , Ayurveda and Biology .. Why thorny plants are not to be kept in house premises ?

You might have seen Demons ,The Asuras fighting with prickly weapons in the Television. Why such a shape is preferred for showing negative weapons ?
The answer is in thorny plants like Cactus which are xerophytic adaptations to store water and to  decrease surface area of the plant surface for  reducing further loss of water in dry areas like deserts.
As per Ayurveda , dryness ,the ruksa guna is found in Vata dosha. So , the black thorny plant itself represents Vata dosha kopa and it shows a kind  of dehydration in the surrounding areas too as it stores water for itself always .
In terms of human emotions , this can be correlated to Rajasic and Tamasic attitude full of greed and Ignorance respectively. The flowers will be rajasic , with attractive colors like red , thorns will be tamasic , black and prickly.
Vastu sastra also shares similar view to avoid thorny plants in house and nearby premises. The dryness can even reflect in personal relationships in the family members in such cases.
Negativity should be avoided and for positive effects , Sastra advocates trees like Peepal tree ,the Aswattha ,Mango tree and plants like Holy Basil ,the Tulasi to be planted in specific directions in the premises.
Plants with insectivorous , creeping and parasitic tendencies also should be discarded similarly.
Medicinal herbs with flowers and fruits can be planted instead of such useless ornamental plants always.