Fabaceae, Solanaceae and Liliaceae · Biology Class 11–12 | StemPy Lab
Course 7.3·Lesson 3 of 3
Fabaceae, Solanaceae and Liliaceae
Fabaceae, the pea family, has a zygomorphic flower with a papilionaceous corolla and a legume. Solanaceae, the potato family, has a radial flower with united petals and epipetalous stamens. Liliaceae, the lily family, is a monocot with six tepals and parallel veins. Each family has its own formula.
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Families of plants
Plants that share many features are placed in one family. A family is described in the same fixed order as a plant: the vegetative characters, the floral characters, a formula, and its uses. Here are three families from NCERT: Fabaceae, Solanaceae and Liliaceae. The first two are dicots, and the third is a monocot.
Fabaceae: the pea family
A floral diagram of a pea flower. A black dot at the top marks the mother axis. A green ring of five sepals, joined by a thin line, is the outermost whorl. Inside it are five petals: one large oval at the top, the standard, which is posterior; two ovals at the sides, the wings; and one yellow oval at the bottom, the keel of two joined petals. Below the centre, nine small stamens sit on a curved line, joined together, and one more stamen sits free at the top. In the middle is one small green ellipse, a single carpel, with ovules along its edge. Below the diagram is the formula: Br, percent sign, K in brackets 5, C 1 plus 2 plus brackets 2, A brackets 9 plus 1, and G with a line under it, 1. A caption says Fabaceae, a bisexual flower.
Pisum sativum, the garden pea, is a typical member. Gram, groundnut, soybean and arhar belong here too.
Vegetative characters
Trees, shrubs and herbs. The roots carry root nodules that hold nitrogen-fixing bacteria.
The stem is erect or a climber.
Leaves are alternate, pinnately compound or simple. The leaf base is swollen, there are stipules, and the venation is reticulate.
Floral characters
The inflorescence is racemose. The flower is bisexual and zygomorphic.
Calyx: five sepals, united.
Corolla: five petals, free, and papilionaceous. There is one large posterior petal, the standard. There are two lateral petals, the wings. Two anterior petals join to form the keel, which encloses the stamens and the pistil.
Androecium: ten stamens, diadelphous: nine are joined and one is free.
Gynoecium: one carpel, with a superior ovary, one chamber and many ovules. The style is single.
The fruit is a legume, and the seed is non-endospermic. The formula is Br%K(5)C1+2+(2)A(9)+1G1, for a bisexual flower.
Uses. Pulses (gram, arhar, sem, moong, soybean), edible oil (soybean, groundnut), a dye (indigo), a fibre (sunhemp), fodder (Sesbania, clover), ornamentals (lupin, sweet pea) and a medicine (muliathi).
Solanaceae: the potato family
A floral diagram of a flower of the potato family. A black dot at the top marks the mother axis. The outer green ring is five sepals joined by a thin line. The red ring inside it is five petals, also joined by a thin line. Five small stamens sit inside the red ring, each joined to the corolla by a short orange line. In the centre is a tilted green ellipse, the ovary of two carpels joined, with a slanting wall across it and a grey swollen placenta carrying many small ovules. Below is the formula: a circle with a plus, K in brackets 5, C in brackets 5, A 5, and G with a line under it, in brackets 2. A caption says Solanaceae, a bisexual flower.
This large family is widespread in the tropics, the subtropics and the temperate zones. Solanum tuberosum, the potato, gives it its nickname.
Vegetative characters
Herbs and shrubs, rarely small trees.
The stem is herbaceous and aerial. In the potato it is also underground, as a stem tuber.
Leaves are alternate and simple, rarely pinnately compound. There are no stipules, and the venation is reticulate.
Floral characters
The flowers are solitary, axillary, or in a cymose cluster. The flower is bisexual and actinomorphic.
Calyx: five sepals, united, and they stay on the fruit.
Corolla: five petals, united.
Androecium: five stamens, epipetalous, which means joined to the petals.
Gynoecium: two carpels, joined and set at a slant. The ovary is superior and has two chambers. The placenta is swollen and bears many ovules.
The fruit is a berry or a capsule, and the seeds are many and endospermous. The formula is ⊕K(5)C(5)A5G(2), for a bisexual flower.
Uses. Food (tomato, brinjal, potato), a spice (chilli), medicines (belladonna, ashwagandha), a smoking crop (tobacco) and an ornamental (petunia).
Liliaceae: the lily family
A floral diagram of a flower of the lily family. A black dot at the top marks the mother axis. A green arc below the flower is a bract, on the side away from the mother axis. Six purple tepals stand in two whorls of three: three larger outer tepals at the top, bottom left and bottom right, and three smaller inner tepals between them. Six small stamens, three and three, each joined to a tepal by a short orange line, form a ring inside. In the centre is a green circle divided into three chambers by three walls, the ovary of three carpels joined, with ovules at the middle of each chamber. Below is the formula: Br, a circle with a plus, P in brackets 3 plus 3, A 3 plus 3, and G with a line under it, in brackets 3. A caption says Liliaceae, a bisexual flower.
This family is a good example of the monocots.
Vegetative characters
Perennial herbs with underground bulbs, corms or rhizomes.
Leaves are mostly basal, alternate and linear. The venation is parallel.
Floral characters
The inflorescence is solitary or cymose, often an umbel-like cluster. The flower is bisexual and actinomorphic.
Perianth: six tepals in two whorls of three, free or united. Sepals and petals look alike.
Androecium: six stamens, 3 and 3, epiphyllous, which means joined to the tepals.
Gynoecium: three carpels, joined, with a superior ovary of three chambers. The placentation is axile and the ovules are many.
The fruit is a capsule, rarely a berry. The seeds are endospermous. The formula is Br⊕P(3+3)A3+3G(3), for a bisexual flower.
Uses. Ornamentals (tulip, Gloriosa), a medicine (Aloe), a vegetable (asparagus) and colchicine, a drug from Colchicum. The onion, Allium cepa, also belongs to this family.
Three families side by side
Pick a family with the slider. Watch the bars change, and read the text above them.
Try it in Python
The program names the family of a flower from its corolla and prints its nickname and fruit.
Practise with new numbers
Common mistakes
Calling the potato a root. The potato tuber is a swollen underground stem.
Mixing up epipetalous and epiphyllous. Stamens joined to petals are epipetalous. Stamens joined to tepals are epiphyllous.
Calling all three families dicots. Liliaceae is a monocot, with parallel veins and tepals.
Giving a pea flower five alike petals. The corolla is papilionaceous: a standard, two wings and a keel.
Mixing up the fruits. A pea pod is a legume. The potato family has a berry or a capsule.
Remember these
Fabaceae: zygomorphic flower, five united sepals, papilionaceous corolla, ten stamens in nine and one, one carpel, a legume, root nodules.
Solanaceae: radial flower, five united sepals, five united petals, five epipetalous stamens, two joined carpels, a berry or capsule.
Liliaceae: radial flower, six tepals, six epiphyllous stamens, three joined carpels, a capsule, bulbs, parallel veins, a monocot.
The formulas are written from the three whorls and the gynoecium, with brackets for fusion.
Check yourself
Try each one on your own first. If you are stuck, open a hint. Then check with Show the answer.
Which family has root nodules, and what do they hold?
Name the three kinds of petal in a papilionaceous corolla.
What is the difference between an epipetalous and an epiphyllous stamen?
Which of the three families is a monocot, and how can you tell from the leaf?
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