Ahnika grantham states the type of flowers that can be offered to Perumal. More specifically, one can find elaborate and special details in Thirukundathai Deiskan’s grantha (text) Nikshepa Chintamani. Vaishnava Nerigal by Swami Desikan has brief explanations on this.
Notes:
It is considered befitting to offer fragrant and colorful flowers. Flowers can be white, pure, and pleasing.
Lotus, jasmine, shenbaga, jadhi, lily, bilva, nandhiaavattai, vakula flowers can be offered.
Seasonal flowers are special.
It is better if the number of flowers offered is more. But, flowers from thorny plants must be avoided.
One should pluck flowers with clean hands by chanting Astramantram.
One should not carry the flowers plucked in bare hands or clothes; a flower basket should be used to gather plucked flowers.
Plucked flowers should be preserved well and must not be allowed to wilt.
Flowers should be strung only with plantain string and not thread.
A person should not adorn the flowers that are set aside for Perumal.
Flowers set aside for other gods must not be offered to Perumal.
Flowers that are to be avoided:
Flowers that are dark, ugly, wild, without fragrance are unfit for the offering.
Flowers that have not bloomed, and that are old, ugly, and wilted.
Flowers that are eaten by insects, torn, and flowers that are with holes.
Flowers that are smelt and that which have been crossed over.
Flowers that are crushed and been stomped by animals.
Flowers are to be avoided from the trees struck by thunder and also from moth and insect infected trees.
Flowers that are grown in unhygienic places and from the crematorium.
Flowers that are grown at the intersection of four roads or from temples of Lord Siva.
Flowers that are touched by unhygienic people or people tainted by an asaucam.
Flowers of the wild plantain tree, tamarind tree, mango tree, poisonous tree, a flame of the forest tree (Palaasa tree), wood apple tree (Vilaam), marutam tree, etc. are unfit for offerings.