All taxa exhibit pluricellular glandular trichomes of different forms and distribution in calyx, corolla and ovary wall and bear a conspicuous floral nectary except for Catalpa bignonioides Walter. In this species the floral nectary is reduced and appears to be a vestigial organ without a secretory function.
Secretory tissue is supplied by phloem.
Raised nectarial stomata were found only in P. ricasoliana, whereas they are at the same level of the epidermis in the remainder species. Extrafloral nectaries were found in flowers of P. jasminoides and P. ricasoliana in the outer surface of the calyx. Those of P. jasminoides are cupular and vascularized while those of P. ricasoliana are patelliform and nonvascularized.