site    plant   flower   status   nectar_present
ek      11      102      n        0
ek      11      103      y        0
ek      11      104      n        1
ek      11      105      y        0
ek      11      106      n        1
ek      11      107      y        0
ek      11      108      n        0

library(lme4)
mod0 <- glmer( status ~ (1 | site/plant), data=your_data_frame, family=binomial )