Influence of Heteromyid Rodents on Oryzopsis hymenoides Germination

Abstract

Seeds (caryopses) of Oryzopsis hymenoides were a preferred food by species of heteromyid rodents on sandy desert rangelands. The rodents were selective in the type of Oryzopsis hymenoides seeds they put in their cheek pouches, rejecting empty seeds and polymorphic forms with reduced germination. The rodents cached some of these highly germinable seeds and emergence of seedlings from these caches was apparently the primary means of stand renewal of Oryzopsis hymenoides in these plant communities. Captivity studies with heteromyid rodents showed that germination of roughly 50% of the seeds in the caches was greatly enhanced by the rodent's removal of the indurate lemma, palea, and pericarp that induced dormancy. An estimated 0.02% of the Oryzopsis hymenoides seeds produced on a favorable moisture year germinated from rodent caches and emerged as seedlings.