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The morphology of flowering plants requires you to know the floral characters and economic importance of the Fabaceae, Solanaceae and Liliaceae families. Instead of memorising each family in isolation, it is faster to learn them side by side. Here is how their features compare.
What are the floral formulas of the three families?
A floral formula uses symbols to describe the symmetry, calyx (K), corolla (C), androecium (A) and gynoecium (G) of a flower.
Fabaceae: % ⚥ K(5) C1+2+(2) A(9)+1 G̲1
Solanaceae: ⊕ ⚥ K(5) C(5) A5 G̲(2) (with an arc joining C and A)
Liliaceae: Br ⊕ ⚥ P(3+3) A3+3 G̲(3) (with an arc joining P and A)
All three families share a superior ovary, indicated by the line under the G (G̲). The numbers in brackets mean the parts are fused. For example, K(5) means five fused sepals Source.
If you find the symbols overwhelming, the Fermi Concept Library has a lesson for every concept in biology to help you understand what each letter means rather than just memorising the strings.
How do their floral characters compare?
The main differences between the families lie in their symmetry, petals and stamens.
Symmetry and petals: Fabaceae flowers are zygomorphic (bilateral symmetry, %), while Solanaceae and Liliaceae are actinomorphic (radial symmetry, ⊕) Source. Fabaceae has a "papilionaceous" corolla: one large standard petal, two lateral wings and two fused anterior petals forming a keel Source. Solanaceae has five fused petals. Liliaceae does not have distinct sepals and petals; instead, it has a perianth of six tepals arranged in two whorls of three Source.
If you are revising how these petals are arranged in the bud, review the aestivation types in flowers to connect these formulas to valvate, imbricate and vexillary patterns.
Stamens (Androecium): The arrangement of stamens is a classic exam question.
Fabaceae: Ten stamens arranged in two bundles of nine and one, known as a diadelphous condition Source.
Solanaceae: Five stamens attached directly to the petals, a condition called epipetalous Source.
Liliaceae: Six stamens attached to the perianth, which is known as epiphyllous Source.
Ovary and placentation: Fabaceae has a single carpel (monocarpellary) with marginal placentation. Solanaceae has two fused carpels (bicarpellary syncarpous) with an obliquely placed, swollen placenta and axile placentation Source. Liliaceae has three fused carpels (tricarpellary syncarpous), also with axile placentation Source. Reading about placentation types in flowers can help you picture how the ovules attach inside these ovaries.
What type of inflorescence does each family have?
Before a flower opens, you can identify its family by how the flowers are grouped on the stem, known as the inflorescence.
Fabaceae: The flowers are arranged in a racemose inflorescence Source. In a racemose pattern, the main axis continues to grow, and the flowers develop laterally in an acropetal succession, meaning the youngest flowers are at the top.
Solanaceae: The inflorescence can be solitary, axillary, or cymose, as typically seen in *Solanum* species Source. In a cymose inflorescence, the main axis terminates in a flower, which limits its growth, and the flowers are borne in a basipetal order.
Liliaceae: Members of this family typically have solitary flowers, or they form cymose inflorescences that often appear as umbellate clusters Source.
What types of fruits and seeds do they produce?
After fertilisation, the ovary matures into a fruit and the ovules become seeds. Each family has a distinct fruit type and seed structure.
Fabaceae: The characteristic fruit is a legume or pod Source. A legume is a simple dry fruit that develops from a single carpel and usually splits open along two sides. The seeds are generally non-endospermic, meaning the embryo stores its nutrients entirely in large, thick cotyledons.
Solanaceae: The fruit is most commonly a berry, like a tomato, or a capsule, like *Datura* Source. The seeds are typically endospermic, where a separate tissue called the endosperm stores food for the developing embryo.
Liliaceae: This family predominantly produces a capsule as its fruit, though some species produce a berry Source. Like Solanaceae, Liliaceae seeds are endospermic Source.
What are the economic examples for NEET?
Questions often ask you to match an economic plant to its family.
Fabaceae (the legume family): This family is the main source of pulses like peas and chickpeas, and edible oils like soybean and peanut Source. It also provides dyes like indigo (*Indigofera*) and medicines like liquorice Source.
Solanaceae (the potato family): Many of our daily vegetables belong here, including tomato, eggplant and potato, alongside spices like peppers Source. It is also the source of the fumigatory tobacco and medicines derived from belladonna Source. For more on how plants store food, explore stem modifications like the potato tuber.
Liliaceae (the lily family): Known for ornamentals like the tulip and *Lilium*, this family also includes *Fritillaria* which is used in traditional medicine Source.
How should you revise plant families?
Use this framework when studying any new plant family:
Identify the symmetry: Is it actinomorphic (⊕) or zygomorphic (%)?
Count the whorls: Are there distinct sepals and petals, or a combined perianth?
Check the stamen attachment: Are they free, diadelphous, epipetalous or epiphyllous?
Locate the ovary: Is it superior or inferior, and what is its placentation?
When a topic requires heavy memorisation, Fermi's AI tutor can build a plan for the session and check your understanding as it goes until the distinctions stick.
