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A close-up of Chinese catalpa

by William (Ned) Friedman, Director of the Arnold Arboretum
November 15, 2015


A close-up of Chinese catalpa

Catalpa_DirectorsBlog16This week at the Arnold Arboretum, Catalpa ovata (the Chinese or yellow catalpa) is beginning to release its stunning lighter-than-air seeds from hundreds of foot-long skinny pods. The trees are otherwise bare, leaves shed earlier in the fall, and each forlorn tree looks as if covered with woody icicles swaying in the breeze (bottom right, 237-2002*C).

Catalpa fruits split longitudinally to reveal a packed inner trove of seeds (lower left, 834-78*B), each with two beautifully fringed wings that help defy gravity and promote more distant dispersal from the mother plant. Under the stereo microscope in the lab, with just the right lighting, the fringe of the seed glows like an electrical storm in the night (upper image). The dark brown inner content of the seed is the short squat embryo that will put forth its exploratory first root in the spring.

Charles Sprague Sargent (first Director of the Arnold) noted (July 15, 1920, Bulletin of Popular Information) that the Chinese catalpa “has been somewhat planted in the United States, although as an ornamental tree it does not have much to recommend it.” A bit harsh given the amazingly beautiful mid-summer flowers (photo here) and small size of this species (30 feet at maturity) compared with its congeners. It does, however, have invasive tendencies.

Ned Friedman, Director of the Arnold Arboretum

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