Wood as a Substratum for Perennial Plants in the Southeast

Abstract

The forests of the Coastal Plain, with their high rainfall and long growing seasons, provide many unique places where seeds may find a favorable habitat in which to germinate. Seed plants ordinarily terrestrial have been found rooting in fallen logs, sawed stumps, natural stumps or snags left by fire, trees killed by lightning, dead tops or stag-heads, dead cypress knees, and in chopped turpentine boxes. Numerous interesting photographs and detailed observations have been obltained during the last two years' field experience in the Coastal Plain of Georgia. At least nine species of perennial herbs, ten shrubs, and five kinds of trees have been observed to have started growing in dead wood. A list of these wood-dwelling perennials is given in Table 1, together with an indication as to their reproductive success and commonness in this habitat. Further observation would doubtless add other species to the list. No cryptogams are included. A few perennials found growing in wood in certain parts of North Carolina are reported separately in Table 2. Various seed plants have been observed growing on wood in northern Florida also. At least half of these species finally reached the fruiting stage. By the time these plants are large enough to reproduce, they have root systems well established in the decayed wood in which they are growing, and those growing in low stumps or logs will have extended their roots through the rotten wood into the mineral soil beneath. In one example, however, a gallberry bush (llex glabra) was found growing in some dead wood high in the top of a living longleaf pine. The roots of this plant penetrated the dead wood in an irregular cavity left by the breaking away of a large limb. Thus the bush was growing and fruiting 50 feet above the ground. Other shrubs have been seen in the tops of dead trunks 30 or 40 feet tall. In Figure 1 the natural stump was about seven feet tall. A slash pine tree about 18 inches tall was found growing in a floating log in a pond, obviously without roots in mineral soil. Stumps of any kind frequently harbor these terrestrials. Figures 2 and 3 are photographs of sawed stumps 3.0 and 2.5 feet tall, respectively. Figure 4 is probably a natural stump although this could not be ascertained with certainty. Figure 5 is doubtless a natural stump. Dead knees of pond bald cypress (Taxodium ascendens Brongniart) sometimes provide a temporary substratum for land plants in the swamps and, of course, the live knees frequently are superficially inhabited by the more simple and primitive members of the plant kingdom. Where these dead knees occur surrounded by water there are no other places for a land plant to grow. Turpentine boxes provide another type of niche in which seed plants