Abstract
Aggregated female cones were found in 192 Pinus halepensis trees growing in 54 populations in Israel, in habitats of vastly differing ecological conditions. All of these trees also carried normal (1-5 in a whorl) female cones. The number of aggregates per tree varied from one to several dozen. Some of the trees formed aggregates every year, after the first year of aggregate formation, while others formed aggregates only once, or at long intervals. Not all cones in the aggregates reached maturity. The number of cones in an aggregate ranged from six to 62, and they were usually smaller than normal. Many of the trees with aggregates showed other abnormalities, e.g., individual female cone scales, proliferated dwarf shoots, three-needled dwarf shoots, shorter cone stalks, needles on cone stalks, larger terminal cones on the main axis in cones formed during the current year, proliferated female cones, and degradation of the main axis above the aggregate. The clusters probably result from replacement of dwarf shoots by ovulate cones.
Highlights
Aggregated cones are one of the reproductive abnormalities of the genus Pinus (Doak 1935; Black 1961; Dorman 1976)
Aggregated cones of Pinus halepensis occur in a low ratio: one tree carrying such cones to several hundred trees without such cones
This proportion is lower than in P. clausa, P. massoniana, P. rigida, and P. thunbergii (Frankis 1980), but higher than in other species in which only a single tree or a few trees are known with such cones (Zobel 1952; Bums and McReynolds 1966; Rudolph et al 1986)
Summary
Aggregated cones (cone clusters) are one of the reproductive abnormalities of the genus Pinus (Doak 1935; Black 1961; Dorman 1976). Cones in a cluster vary from fewer than 10 to more than 100 (Carlisle 1958; Frankis 1980). Some trees forming aggregated cones display other developmental abnormalities: female and male cones formed at the same position, small mature female cones, and dwarf shoots with more needles than usual (Black 1961; Pollack and Dancik 1979; Lemoine-Sebastian 1982). A few studies have been devoted to the genetics of cone clustering (Teich and Holst 1969; Rudolph et al 1986). Several authors suggest a genetic control of cone clustering (Zobel 1952; Carlisle 1958; Frankis 1980)
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