A Grammatical Dictionary of Botanical Latin

ypsil-, ypsili-, ypsilo-: in Gk. comp. Y-shaped [ > Gk. upsilon (ypsilon), the Greek letter 'u' transliterated into Latin as 'y'; the Gk. initial 'u' is unaspirated (spiritus lenis.]; see 'Y-shaped.' Actually the Greek word means 'upsilon-shaped,' and refers, not to the 'u' or 'lower case' Greek letter, but its capital, which resembles the capital letter 'Y' in both Greek and Latin;

- ypsilo-stylus: with a Y-shaped style.

NOTE: since the initial upsilon is always aspirated one might have expected this prefix to be spelled 'hypsil-.'

NOTE: The fungus genus Ypsilonia has spores that are Y-shaped (Ainsworth & Bisby), as presumably Ypsilospora Cummins.

Ypsilactyle; Ypsilandra Franch.; Ypsilopus Summerh.

NOTE: the name Ypsilopus Summerhayes derived the generic name from two Greek words "the letter Y" and "foot" to denote the "Y" shaped stipe of the pollinarium (American Orchid Society website, July 2013).

NOTE: in some dictionaries this prefix is considered to represent ‘U-shaped,’ i.e., the lower case Greek upsilon. This does not appear to be the case. The adjective for the lower case upsilon appears to be hyoid, q.v.