Description of Some Important Families: Have you ever wondered how many plant species we have and what is a flowering plant? Flowering plants or angiosperms are the most abundant plant group present on earth right now, characterized by the enclosure of the ovules and flowers. They include more than 220,000 species exhibiting a wide range of ecological habitats.

According to a rough estimate, approximately 165,000 species are of dicots, and about 55,000 species are of monocots. Such a wide range of flowering plants are identified, described, and classified according to their morphology and anatomy. In this article, we will learn about the description of some important families of angiosperms.

Families of Flowering Plants

The most diverse plant group present currently on earth is flowering plants known as angiosperm or Magnoliophyta with 64 orders, 416 families, approximately 13,000 known genera, and 300,000 known species. Further, these flowering plants are divided into two classes Dicotyledonae (seeds with two cotyledons) and Monocotyledonae (seeds with one cotyledon).

Different characteristics of a family are the diagnostic features that enable us to differentiate them. These diagnostic features are mainly based on floral characters like the sexuality of flowers, symmetry of flowers, position of the ovary concerning floral whorls, bracts, and conditions of calyx, corolla, androecium, and gynoecium.

For a systematic study and quick comprehension of all the diagnostic features of a family, these characters are symbolized and put in the form of a floral formula. The floral diagram is a diagrammatic representation of the transverse section and floral buds, providing extra information like placentation, the position of the mother axis, aestivation, etc.

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Let us read about two  important families of dicot and one family of the monocot plant:

Fabaceae

It is distributed worldwide with about 400 genera and 12000 species. This family was earlier called Papilionoideae, a sub-family of the family Leguminosae.

Systematic Position

• Class- Dicotyledonae
• Subclass- Polypetalae
• Series- Calyciflorae
• Order- Rosales
• Family- Fabaceae

Vegetative Characters

• Habit: Plants are mostly herbs—however, shrubs, trees, and climbers are also common.
• Root: Taproot in which the lateral branches are mostly nodulated (Root nodules contain nitrogen-fixing bacteria Rhizobium).
• Stem: Herbaceous or woody, erect or climber by tendrils. Leaves: Alternate, rarely simple, generally pinnately compound, stipulate, leaf base pulvinate, venation reticulate, leaves or leaflets modified into tendrils.

Floral Characters

• Inflorescence: Racemose or solitary.
• Flower: Pedicellate, bractate, bisexual, zygomorphic, perigynous, occasionally hypogynous, pentamerous.
• Calyx: Sepals five, gamosepalous, valvate/imbricate aestivation.
• Corolla: Petal five,  polypetalous, papilionaceous, consisting of a posterior standard, two lateral wings, two anterior ones forming a keel (enclosing stamens and pistil), vexillary aestivation. 
• Androecium: Ten, diadelphous (9 are fused into a tube and 1 is), anther dithecous.
• Gynoecium: Ovary superior, monocarpellary, unilocular with many ovules, style single, many ovules in two alternate rows.
• Fruit: A legume or pod.Seed: One to many, non-endospermic.

Economic Importance

1. Pulses: This family is the source of several pulse crops such as Gram(chana), arhar ( Pigeon pea), moong( Green gram), soyabean, etc.
2. Fodder: Trifolium, Sesbania, etc.
3. Edible oil: Soyabean and groundnut are used as cooking oil, preparation of soaps, cosmetics, etc.
4. Dyes: Indigo dye obtained from Indigofera.
5. Fibres: Plants belonging to this family are also used as fodder, e.g., Sunhemp
6. Ornamental: Common ornamentals are lupin( Lupinus), sweet pea (Lathyrus odoratus)
7. Medicines: The roots of  Glycyrrhiza glabra (Muliathi) are used in relieving inflammation and treating gastric ulcers; seeds of Butea monosperma have antifungal and anthelmintic properties.

Example: Pisum sativum (pea)

• Habit: An annual, cultivated, ornamental, climbing herb.
• Root: Tap-root with root nodules.
• Stem: Herbaceous, aerial weak, branched, winged, hollow, green, climbing.
• Leaf: Ramal and cauline, alternate, petiole, upper leaflets are modified into tendrils, stipulate.
• Inflorescence: Racemose or Solitary axillary.
• Flower: Pedicellate, bractate, bisexual, zygomorphic.
• Calyx: Sepals 5, gamosepalous, valvate aestivation, green, hairy, persistent.
• Corolla: Petals 5, polypetalous, vexillary aestivation, papilionaceous.
• Androecium: Stamens 10, Diadelphous.
• Gynoecium: Monocarpellary, Unilocular, ovary half inferior, marginal placentation, style long and curved, covered by the keel.
• Fruit: Legume.
  

Solanaceae

It is a large family, represented by about 90 genera and 2800 species commonly called the potato family. It is widely distributed in tropics, sub-tropics, and temperate zones.

Systematic Position

• Class- Dicotyledonae
• Subclass- Gamopetalae
• Series- Bicarpellatae
• Order- Polyminales
• Family- Solanaceae

Vegetative Characters

• Habit: Mostly herbs, sometimes shrubs or trees; rarely vines.
• Root: Taproots.
• Stem: Herbaceous, rarely woody, aerial, erect, cylindrical, solid, branched or hollow, hairy or glabrous (smooth), underground stem in potato (Solanum tuberosum).
• Leaves: Alternate, simple, rarely pinnately compound, exstipulate, hairy, reticulate venation.

Floral Characters

• Inflorescence: Solitary, axillary, or cymose as in Solanum.
• Flower: Bractate or ebractate, pedicillate, bisexual, actinomorphic, pentamerous, hypogynous.
• Calyx: Sepals five, united, persistent, valvate aestivation, gamosepalous.
• Corolla: Petals five, gamopetalous, valvate aestivation.
• Androecium: Stamens five. Epipetalous, anthers bithecous.
• Gynoecium: Bicarpellary, syncarpous, ovary superior with oblique septa, bilocular, placenta is swollen with many ovules, placentation axile.
• Fruit: A many-seeded berry or capsule.
• Seed: Many, endospermous. Floral formula:

Economic Importance

• 1. Food: This family includes numerous plants producing vegetables and other edible products, for example- Solanum tuberosum (Potato), Lycopersicon esculentum (tomato), Solanum melongena (brinjal), Capsicum annuum (Chillies), etc.
• 2. Tobacco: It comes from the dried and aired leaves of Nicotiana tabacum. It is a fumigatory plant.
• 3. Medicine: Plants such as Atropa belladonna (Atropine), Hyoscyamus niger (Henbane), Datura, etc., yield many valuable drugs.
• 4. Ornamental: Common ornamental plants are Petunia, Cestrum, etc.

Example: Solanum nigrum

• Habit: An annual wild herb.
• Stem: Herbaceous, aerial, erect, branched, cylindrical, solid, green, smooth.
• Leaf: Ramal and cauline, alternate, petiolate, unicostate, reticulate venation.
• Inflorescence: Cymose, extra-axillary cyme.
• Flower: Sepals 5, gamosepalous, valvate aestivation, green
• Corolla: Petals 5, gamopetalous, campanulate, valvate aestivation.
• Androecium: Stamens 5, polyandrous, epipetalous.
• Gynoecium: BIcarpellary, syncarpous, bilocular, many ovules in each locule, superior ovary, axile placentation.
• Fruit: Berry.

Liliaceae

It is commonly called the lily family, including 250 genera and 3700 species. The plants belonging to this family are monocotyledonous. They are widely distributed worldwide.

Systematic Position

• Class- Monocotyledonae
• Series- Coronarieae
• Family- Liliaceae

Vegetative Characters 

• Habit: Mostly perennial herbs with underground bulbs, corms, rhizomes.
• Roots: Adventitious, fibrous.
• Stem: Aerial or underground, herbaceous or woody. Leaves: Mostly basal, alternate, linear, exstipulate with parallel venation.

Floral Characters

• Inflorescence: Solitary/cymose, often umbellate clusters.
• Flower: Bisexual, actinomorphic.
• Perianth: Tepal six (3 + 3). often united into a tube, valvate aestivation.
• Androecium: Stamen six, (3 + 3).
• Gynoecium: Tricarpellary, syncarpous ovary superior, trilocular with many ovules, exile placentation.
• Fruit: Capsule, rarely a berry.
• Seeds: Endospermous. Floral Formula:

Economic Importance

• 1. Food: Young shoots and root tubers of Asparagus species are cooked;  Bulbs of Allium cepa and Allium sativum are used as vegetables.
• 2. Medicines: Aloe is a source of medicine. Medicated oil is prepared from the roots of Asparagus.
• 3. Ornaments: The common ornamental plants are Gloriosa and tulip.
• 4. Colchicine: Colchicumautumnale yields colchicine which is used in the doubling of chromosomes.

Example: Allium cepa

• Habit: An annual herb.
• Root: Adventitious root.
• Stem: Reduced underground (bulb).
• Leaf: Radical, rosette-like, sessile, parallel venation.
• Inflorescence: Umbellate cluster borne on an aerial peduncle.
• Flower: Pedicellate, ebractiate, bisexual, actinomorphic, hypogynous, trimerous.
• Perianth: Tepals 6, arranged in 2 whorls of 3 each, tepals of one whorl alternating with those of the other whorl.
• Androecium: Stamens 6, arranged in two whorls.
• Gynoecium: Tricarpellary, syncarpous, trilocular, two ovules in each locule, axile placentation.
• Fruit: Capsule.

Summary

A wide range of flowering plants is present on our earth, grouped into various families and subfamilies based on certain morphological characters. There are certain important families like Fabaceae family or pea family showing diadelphous anther along with vexillary aestivation and nodulated roots for nitrogen fixation; Solanaceae family or potato family showing association of corolla with androecium (epipetalous) and gamosepalous calyx. Solanaceae family shows a bisexual flower with valvate aestivation; Liliaceae family or Lilly family have root bulbs with parallel venation leaves, and their flowers are hypogynous with the perianth.

FAQs on Description of Some Important Families

Q.1. State the example of the Solanaceae family.
Ans: Solanaceae family includes  Petunia, Lycianthes, Atropabelladonna, Mandragora, and Datura.

Q.2. State the examples of the Fabaceae family.
Ans: The Fabaceae family includes legumes like Pisum sativum, Arachis hypogaea, Phaseolus vulgaris, Glycine max, etc.

Q.3. State the examples of the Liliaceae family.
Ans: The Liliaceae family includes Allium cepa, Aloe, Yucca, Lililum, etc.

Q.4. What is vexillary aestivation?
Ans: Vexillary aestivation is the arrangement of the corolla in which there is a large petal vexillum with two petals known as wings and two fused petals known as keels.

Q.5. Which family is known as the potato family?
Ans: The Solanaceae family is also known as the potato family.

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