How to identify fabaceae and ,it's subfamilies

Answer 1

The Fabaceae family, commonly known as the legume, pea, or bean family, is one of the largest families of flowering plants. It includes a diverse range of species, from herbs to shrubs, trees, and vines. Identifying members of the Fabaceae family and distinguishing its subfamilies can be accomplished through various morphological, reproductive, and anatomical characteristics. Here are some key features and how to identify the family and its main subfamilies:

General Characteristics of Fabaceae:

1. Leaves:

   • Compound leaves, typically pinnate, palmately compound, or simple.
   • Often have stipules (small leaf-like structures at the base of the leaf stalk).

2. Flowers:

   • Usually zygomorphic (bilaterally symmetrical) but can be actinomorphic (radially symmetrical) in some subfamilies.
   • Typically five petals; the arrangement of petals may vary among subfamilies (e.g., banner, wings, and keel in papilionoid flowers).
   • Presence of a unique floral structure called the "banner, wings, and keel" (particularly in the subfamily Papilionoideae).

3. Fruit:

   • Fruit type is typically a legume, which is a pod that splits open along two seams (dehiscent) to release seeds.
   • Seeds often contain nodules that host nitrogen-fixing bacteria.

4. Roots:

   • Many species form symbiotic relationships with nitrogen-fixing bacteria (Rhizobia) in root nodules.

Major Subfamilies of Fabaceae:

1. Papilionoideae (or Faboideae):

   • Characteristics: Flowers usually have a distinct banner petal, two wing petals, and two fused keel petals. Leaves are typically compound.
   • Examples: Peas (Pisum sativum), alfalfa (Medicago sativa), and clovers (Trifolium spp.).

2. Mimosoideae:

   • Characteristics: Flowers are often actinomorphic with many stamens that can be quite showy, making the flower heads look fluffy. Leaves can be compound or once-pinnate.
   • Examples: Mimosa (Mimosa pudica) and Acacia species.

3. Caesalpinioideae (now often considered a paraphyletic group):

   • Characteristics: Flowers can be variously shaped; petals can be distinct but are often less showily arranged than in Papilionoideae. Some species have legume-shaped pods.
   • Examples: Cassia (Cassia spp.) and Cercis (redbud).

Steps to Identify Fabaceae and Its Subfamilies:

1. Observe the plant's overall morphology: Note the growth form (herb, shrub, tree).

2. Examine the leaves: Check for compound leaves and stipules.

3. Analyze the flowers:

   • Assess symmetry and petal arrangement.
   • Observe the number of stamens and their arrangement.

4. Check the fruit type: Look for legume pods and their characteristics (length, shape, dehiscence).

5. Consider the habitat: Many members of the Fabaceae family are found in specific ecosystems.

By carefully examining these characteristics, you can effectively identify members of the Fabaceae family and differentiate between its subfamilies. Field guides or regional plant identification guides can also provide additional help and visual illustrations.