Cupressaceae
More on Morphology
More on Morphology
Cupressaceae both exists as tall and erect trees. These trees have a single, clearly marked main axis, with strong, high lateral axes. They are mostly evergreen, but some species of Taxodiaceae are deciduous. Cupressaceae also has several species that are shrubs. These shrubs are procumbent, which means that the branches are close to the ground and do not attain any considerable height, because the terminal axes are weaker than the lateral ones. The size of the adult plants can range from about 3-5 meters tall (juniper) to the largest tree in the world, the Giant Sequoia, which can grow up to 100 meters tall and 12 meters in diameter.
The bark of the Cupressaceae and Taxodiaceae can vary from thin to thick and can be scaly, furrowed or smooth (especially in young trees). The color of bark varies with species, age of the tree, part of the trunk and environmental factors, but is usually some gradation of brown or gray.
The leaves of young Cupressaceae and Taxodiaceae plants are needle-like and abscising. However, the leaves of the adult Taxodiaceae diverge into needle forms, scale forms, and sickle-shaped forms. These leaves are spirally arranged, except in Metasequoia. The adult Cupressaceae leaves are usually small and scale-like. These are rarely needle-like in the adult form. They grow in opposite pairs or in whorls of three and sometimes in whorls of four. Adult Cupressaceae leaves are often lateral on flattened branches.
Both the Taxodiaceae and Cupressaceae have monoecious species, but the Cupressaceae has some dioecious species. The characteristics of the male cones are that they are small, solitary, and terminal on short shoots. The male cones can be spherical or oblong and they live in capitate forms (congregated together in a clump). Some male cones of Taxodiaceae plants are not terminal on the branches, but are axillary and panicle (spread out over the whole plant). Pollen grains of the Cupressaceae and Taxodiaceae are globose and in distinct sacs. The pollen grains of Taxodiaceae have no airsacs and no wings. However, the Cupressaceae pollen grains have two airsacs, which enable the grain to disperse over a large distance, by wind.
The characteristics of the female cones of Cupressaceae and Taxodiaceae are that they are generally larger than the male cones of the same species. They are usually solitary and globular. The female cones of Cupressaceae can be woody, leathery or semi-fleshy. They exist either open or closed forms and either peltate (shaped like a shield) or thin and flat. The scales of the female cones of Cupressaceae are woody or fleshy and in few opposing pair. The scales meet at the edges and are partially or wholly adnate (one side attached to the stem), decussate (in pairs with each pair at a right angle to the next pair above or below it), or whorled (growing in a circle around the same point in the axis). There are a small number of fertile scales, with one or more ovules on each fertile scale. The bract scale of the female Cupressaceae cone is not externally visible. The female cones of the Taxodiaceae plants are terminal on shoots and conelet-like. These cones open when ripe. The scales of the female Taxodiaceae cones originate from the seed bulge and are woody when ripe. The fertile scales are more or less adnate to the bract scale. At first, the fertile scale is bulging, but then it enlarges and surpasses the bract scale. There are generally two to nine erect or inverted ovules for each fertile scale.
The seeds of both the Taxodiaceae and Cupressaceae have compressed, narrow wings on both sides. However, some species of Cupressaceae have seeds which do not have wings. The seeds are either united into a seed pit or are distinct. Fertilization follows pollination after different periods of time depending on the genera and species of the plant. In most Taxodiaceae and Cupressaceae plants, it takes only one to two months, but it can range up to one year in Juniperus sabina. In the Cupressaceae, there are generally two to six cotyledons (embryonic leaves), whereas in the Taxodiaceae, there can be two to nine cotyledons.
