| Popis: |
Examination of Armillaria rhizomorphs collected from the soil of aspen (Populus tremuloides Michx. and P. grandidentata Michx.) sprout stands in northern Wisconsin revealed a complex structure consisting of four distinct zones. The innermost area (zone 4) consisted of interspersed fiber hyphae and broader, tubelike hyphae and was surrounded by a region composed of fiber hyphae only (zone 3). In thick (usually > 2 mm in diameter) rhizomorphs, zone 4 appeared as a distinct, dense central core that was darker than zone 3. In all rhizomorphs zones 2 and 1 were continuous to the exterior. Several layers of broad, thin-walled cells comprised zone 2. Toward the outside of zone 2 these cells gradually became thicker walled and merged with a zone of fused, thick-walled cells with very small lumens (zone 1). Zone 2 was less distinct in thicker rhizomorphs, probably as a result of gradual thickening of cell walls and addition of these to zone 1. The types of hyphae observed and their organization are discussed in relation to previous descriptions of rhizomorphs attributed to Armillaria mellea. |
