Odontoglossums, which Miss Barstow surprises Archie by preferring to the Cattleyas, are very odd-looking flowers. Paphiopedilums, the slipper orchids, seem even less Terran. Orchids are the Surrealists of the plant kingdom. The most unnerving orchid of all is Bollea violacea, a simple five-petalled pink flower whose center looks exactly like a screaming mouth. I haven't read every Nero Wolfe book, but I've read about 15 of them, and I can't recall a single mention of an ugly orchid, or even one whose strangeness overwhelms its beauty.
Characters favor one sort over another, but they're never repelled or nonplussed.
Also, their first impressions are always favorable. Often, seeing a new kind of orchid, I'm struck first by its strangeness, and see its beauty only gradually. Or sometimes it's the other way around. Maybe Wolfe only collects the most beautiful orchids. That would fit his character.