Raceme and glumes arranged in two opposite rows along the spikelet. Examples occur on rice (species "Oryza sativa") and wheat (genus "Triticum"), both grasses. An ament or catkin is very similar to a spike or raceme, "but with subtending bracts so conspicuous as to conceal the flowers until pollination, as in the pussy–willow, alder, [and] birch...". These are sometimes called amentaceous plants. A spadix is a form of spike in which the florets are densely crowded along a fleshy axis, and enclosed by one or more large, brightly–colored bracts called spathes. Usually the female flowers grow at the base, and male
12-oxophytodienoate reductase 12-oxophytodienoate reductase 12-oxophytodienoate reductase (OPRs) is an enzyme of the family of Old Yellow Enzymes (OYE). OPRs are grouped into two groups: OPRI and OPRII – the second group is the focus of this article, as the function of the first group is unknown, but is the subject of current research. The OPR enzyme utilizes the cofactor flavin mononucleotide (FMN) and catalyzes the following reaction in the jasmonic acid synthesis pathway: This reaction occurs in peroxisomes in plants. Several isozymes have been discovered, with varying substrate stereospecificity: three in "Lycopersicon esculentum", 13 in "Oryza sativa", and five in "Arabidopsis thaliana".