Question
My 5 year old was just diagnosed with allergies to Maple trees and I wondered if water maples are in the same family.

Answer
Common names are sometimes misleading. Sometimes different trees have the same common name. There is a water maple and it is in the maple family.

Maple (Acer spp.) contains about 120 species native to Asia [16], North America [13],
Mexico and Guatemala [1], and the European/Mediterranean region [6], with the rest in Eurasia, Malaysia and northern Africa. The Maples can be separated into two groups based on the ray widths of their microscopic anatomy, the soft maple group and the hard maple group. Species within each group look alike microscopically. Acer is the classical Latin name of maple.

The scientific name is Acer saccharinum*- the common names are creek maple, papascowood, river maple, silver maple, silverleaf maple, soft maple, swamp maple, water maple, white maple.

You should ask what part of the maple he is allergic to if it is the flowers then these only are in the spring and last a short time.