Easily-confused!
If your specimen is/has a:with stems/​leaves ar­ranged:and the leaves:then you have:
☙ her­ba­ceous,
vertical stem interior=​hollow, cham­bered with periodic diaphragms like bamboo
╟ alternate are ♤ heart-shaped except for a __ flat-base lookalike Japanese knotweed  Fallopia japonica.
woody stem (tree) are ♤ heart-shaped with a ∪ round­ed-base lookalike eastern redbud  Cercis canadensis.
╫ opposite this plant, please continue below …
taper at both ends, and
pass the dogwood leaf test
lookalike flowering dogwood  Cornus florida.

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Learn more about northern or hardy catalpa Catalpa speciosa

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