You know how opponents of gay marriage often express concern that allowing it will lead to other nontraditional marriages, like those between people and, say, cows? Well, their worst nightmare will come true in todays The Art Guys Marry a Plant. As part of the ongoing exhibition No Zoning: Artists Engage Houston at the Contemporary Arts Museum, the Guys (Michael Galbreth and Jack Massing) will tie the knot with a live oak sapling, which they purchased for $15, in a ceremony conducted by an ordained minister. This latest bit of behavior art from the Guys is meant to question both social norms and art norms; the inspirational spouse will eventually be planted with a plaque indicating how it broke the mammal-mammal marriage barrier. The ceremony will be in the Lillie and Hugh Roy Cullen Sculpture Garden (Montrose at Bissonnet), followed by a reception at the Contemporary Arts Museum Houston. 11 a.m. 5216 Montrose. For information, call 713-284-8250 or visit www.camh.org. Free.