A muscle fiber contains many myofibrils, which are cylinders of muscle proteins. These proteins allow a muscle cell to contract. Myofibrils contain two types of filaments that run along the long axis of the fiber, and these filaments are arranged in hexagonal patterns. There are thick and thin filaments.hese proteins allow a muscle cell to contract. Myofibrils contain two types of filaments that run along the long axis of the fiber, and these filaments are arranged in hexagonal patterns. There are thick and thin filaments.
Cocklebur (Xanthium strumarium L.) is a large, annual broad-leaved weed with an erect, branched stem and broadly triangular leaves (Figure 1). The stem is rough-hairy, spotted with purple and up to 1.5 m high. The leaves are alternate on the stem, with toothed or lobed margins and rough-hairy surfaces.
Description [edit]. Cockleburs are coarse, herbaceous annual plants growing to 20â47 inches (51â119 cm) tall. The leaves are spirally arranged, with deeply toothed margins. Some species, notably Xanthium spinosum, are also very thorny with long, slender spines at the leaf bases.escription [edit]. Cockleburs are coarse, herbaceous annual plants growing to 20â47 inches (51â119 cm) tall. The leaves are spirally arranged, with deeply toothed margins. Some species, notably Xanthium spinosum, are also very thorny with long, slender spines at the leaf bases.