PLANT FAMILY CHARACTERISTICS Plant families are separated according to structural differences in flowers, fruit, and seed. Genera that share similar structures are grouped within a particular family. While some plant families, such as Orchidaceae (orchid) and Asteraceae (sunflower family) have several hundred members, others such as Ginkgoaceae (ginkgo) have a single member. As the group with the greatest number of closely related plants, the family taxon provides a starting point for narrowing the search for an unknown plant. In addition to shared morphological characteristics, the family taxon provides information about evolutionary adaptations for growth conditions as well as methods for propagation. One of the most comprehensive references for angiosperms is Flowering Plant Families of the World by V. H. Heywood (2007). The morphological characteristics for some families and genera commonly found in landscapes and gardens are summarized below. Images of the representative genera
PLANT MORPHOLOGY – FLOWERS AND FRUIT The most significant patterns, in terms of evolutionary relationships, involve reproductive structures, such as the number and arrangement of flower parts, or the structure of cones. While the size and shape of vegetative structures such as leaves and stems are relatively plastic or changeable, the basic patterns of reproductive structures change little over time. Although access to flowers and fruit may be seasonal, digital resources and herbarium samples allow the identification of patterns and relationships within plant taxa. FLOWER AND INFLORESCENCE MORPHOLOGY Flower shape, color, and markings are all valuable features for plant identification. Figure 16.1 illustrates some flower shapes that are commonly used for identification purposes. Figure 16.1 Flower corolla shapes. A typical angiosperm flower is borne on a peduncle (stalk) and is composed of the receptacle, sepals (calyx), petals (corolla), stamens, and pistil (carpel). Flower par