Lodicule disposition affects whether a floret is open or closed flowering. The wild-type phenotype is the frontal ‘bib’ type lodicule disposition, which results in open flowering. Cleistogamy (closed flowering) is due to the clasping ‘collar’ type lodicule disposition, and results in an alost entirely autogamous habit due to the release of pollen within the closed flower. Cleistogamy also provides a means of escape from cereal head blight infection. A Mendelian genetic locus controlling open/closed flowering, termed CLYSTOGAMOUS 1 (CLY1), maps to chromosome 2H, and is encoded by the gene AP2 (PMID: 20018663).
This triat is scored during national varietal registration trials, as described by UPOV guidelines: "Grain: disposition of lodicules" (UPOV character 27. Scores: 1 = frontal ‘bib’ type, open flowering; 2 = clasping ‘collar’ type, closed flowering).
see http://www.upov.int/test_guidelines/en/list.jsp