GERMINATION AND EARLY GROWTH OF WESTERN LARCH (LARIX-OCCIDENTALIS), ALPINE LARCH (LARIX-LYALLII), AND THEIR RECIPROCAL HYBRIDS

Reciprocal cross pollinations between western larch (Larix occidentali s Nutt.) and alpine larch (L. lyallii Parl.) were done in Spring, 1991 . The cross to alpine larch females was highly successful; 63% of the seeds developed mature embryos and 79% germinated. However, the cross to western larch females resulted in only 4% filled seed of which 68% germinated. Open-pollinated western larch and alpine larch averaged 26 and 32% filled seed with 48 and 44% germination, respectively. Less t han 1% of the alpine larch hypocotyls were reddish in color; most of t hem were green. About 15% of the western larch and about 17% of the hy brids from alpine larch females had reddish hypocotyls, whereas hybrid s from western larch females were intermediate between western larch a nd alpine larch. Hybrid seed began germinating before the parental typ es and initial height growth exceeded that of the parental types. Howe ver, 4 months following germination, western larch seedlings were ca. four times taller than the hybrids and 10 times taller than alpine lar ch. Stems of hybrids were significantly thicker than those of either w estern larch or alpine larch. Hybrid seedlings are robust, stocky, and may be useful in revegetating cold, moist sites between the elevation al ranges of alpine and western larch.