Cone and seed morphology of western larch (Larix occidentalis), alpine larch (Larix lyallii), and their hybrids.
1993
Carlson C.E. | Theroux L.J.
Although western larch (Larix occidentalis Nutt.), alpine larch (Larix lyallii Parl.), and their natural hybrids can be recognized by morphological traits other than those of the reproductive structures, analyses of cone morphology suggest that cone shape and several variables representing bract and scale features, including the ratio of bract length to scale length, also distinguish the taxa. Western larch cones have a smaller length:width ratio than alpine larch. Dry hybrid cones are similar in shape to western larch but when wet they emulate alpine larch. The ratio of bract length to scale length was smallest (1.14) for western larch, intermediate (1.20) for alpine larch, and highest (1.38) for the hybrids. Bract length:width ratio was highest (2.67) for alpine larch, lowest (2.42) for western larch, and intermediate (2.47) for the hybrids. Seeds are less useful in recognizing hybrids, but are distinctive between western and alpine larch. Seeds of alpine larch are much larger than western larch and are triangular in shape; they are easily distinguished from seeds of natural hybrids because hybrid seeds closely resemble western larch seeds.
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