Lamiaceae family full discription slide.pptx

Lamiaceae (Labiatae)
Morphology • Taxonomy • Floral Biology • Economic & Medicinal Importance
MSc Botany / Life Science — Classroom Teaching

Learning Objectives
Recognize the diagnostic vegetative and reproductive characters of Lamiaceae.
Interpret the inflorescence, floral morphology, floral formula and floral diagram.
Identify representative genera and economically important species.
Relate family characters to taxonomy, essential oils and traditional medicine.
Lamiaceae | MSc Teaching PPT • 2

Family at a Glance
Large and cosmopolitan family of aromatic herbs, shrubs and subshrubs.
Most characteristic members have opposite, often decussate leaves and quadrangular stems.
Flowers are commonly bisexual and zygomorphic with a bilabiate corolla.
Ovary is deeply 4-lobed with a gynobasic style; fruit usually separates into four nutlets.
Many members are rich in essential oils and are important in medicine, flavouring and perfumery.

Systematic Position
Kingdom: Plantae
Clade: Angiosperms → Eudicots → Asterids
Order: Lamiales
Family: Lamiaceae Martinov (also known historically as Labiatae)
Modern classification recognizes Lamiaceae as a diverse family within Lamiales.

Distribution & Habitat
Cosmopolitan; especially diverse in warm temperate, Mediterranean and subtropical regions.
Common in open habitats, grasslands, forest margins, rocky slopes and cultivated areas.
Many species tolerate relatively dry conditions and produce aromatic oils.
Representative genera occur across India and are widely cultivated.

Habit
Predominantly annual or perennial herbs.
Also includes shrubs and subshrubs; a few taxa may become small woody plants.
Many species are aromatic because of glandular trichomes containing volatile oils.
Examples: Ocimum, Mentha, Salvia, Leucas and Pogostemon.

Root
Usually a well-developed taproot system in herbaceous species.
Adventitious roots may develop in creeping or vegetatively propagated plants.
Root characters are generally less diagnostic than stem, leaf and floral characters.
Root systems support anchorage and water/mineral uptake in diverse habitats.

Stem
Usually erect, branched and characteristically quadrangular in cross-section.
Four prominent angles may be associated with collenchymatous tissue.
Young stems are often green and herbaceous; older portions may become somewhat woody.
Glandular and non-glandular trichomes are common.
Teaching point: the quadrangular stem is a useful field clue, but not an absolute character for every species.

Leaves
Leaves usually opposite and decussate; each pair is oriented roughly at right angles to the next.
Usually simple, exstipulate and petiolate.
Margins may be entire, serrate, crenate or deeply divided depending on genus.
Oil glands and glandular hairs can make leaves strongly aromatic.
Venation is generally reticulate.

Inflorescence: Verticillaster
Characteristic inflorescence in many Lamiaceae is the verticillaster.
It appears whorled because two condensed dichasial cymes arise at a node.
Each apparent cluster is therefore a cymose structure rather than a true whorl.
Flowers may be sessile or shortly pedicellate, often subtended by bracts.
Examples commonly illustrated with Salvia, Ocimum and Leucas.

Flower: General Features
Usually bisexual, complete, hypogynous and zygomorphic.
Flowers are commonly bracteate and arranged in cymose clusters.
Perianth differentiated into a gamosepalous calyx and gamopetalous corolla.
Strong bilateral symmetry is associated with specialized pollination.

Calyx
Usually 5 sepals, united (gamosepalous).
Often persistent and sometimes accrescent in fruit.
May be tubular, campanulate or distinctly bilabiate.
Five teeth/lobes commonly indicate the pentamerous construction.
Persistent calyx can aid in fruit protection and identification.

Corolla
Usually 5 petals, united (gamopetalous).
Commonly bilabiate: an upper lip and a lower lip.
Upper lip is often 2-lobed; lower lip commonly 3-lobed.
Corolla tube and lips provide a landing/guide surface for pollinators.
Shape varies considerably among genera and is important for identification.

Androecium
Usually 4 stamens, commonly didynamous: two longer and two shorter.
Stamens are epipetalous and arise from the corolla tube.
Some genera have only 2 fertile stamens; Salvia shows highly specialized stamens.
Anthers are typically bilobed and release pollen through longitudinal dehiscence.
Stamen number and configuration are important generic characters.

Gynoecium
Usually bicarpellary and syncarpous.
Ovary is superior and becomes deeply 4-lobed at maturity.
Each ovary lobe generally contains one ovule.
Style is gynobasic, arising from the base between the four ovary lobes.
Stigma is commonly bifid or two-branched.
Four-lobed ovary + gynobasic style

Fruit
Fruit commonly a schizocarp that separates into four one-seeded nutlets.
Each nutlet represents a mericarp derived from the four-lobed ovary.
Nutlets may be smooth, sculptured or mucilaginous depending on species.
Fruit type is highly useful in recognizing the family.

Seed
Seeds are generally small and exalbuminous or with little endosperm at maturity.
Embryo is well developed and usually straight or nearly straight.
Seed surface may show diagnostic sculpturing in some genera.
Dispersal is often by gravity, animals, water or attachment to substrates depending on species.

Floral Formula
Generalized formula: Br, Brl, /%, , K(5), C(5), A4–2, G(2).
⊕ ⚥
Ovary is superior; the bicarpellary ovary becomes 4-lobed.
Gynobasic style is a key family character.
Note: floral details vary among genera, so the formula represents a generalized family pattern.

Floral Diagram — How to Read It
Start from the outer whorl: 5 fused sepals forming the calyx.
Next identify the 5 fused petals forming the bilabiate corolla.
Locate the usually 4 epipetalous stamens; note possible reduction to 2.
At the centre, show the superior 4-lobed ovary and gynobasic style.
Use the diagram to connect symmetry and organ fusion with the written floral formula.
Simplified floral teaching schematic

Diagnostic Characters
1. Quadrangular stem (common field clue).
2. Opposite, often decussate leaves; exstipulate.
3. Aromatic foliage due to glandular trichomes in many taxa.
4. Verticillaster or condensed cymose inflorescences in many members.
5. Zygomorphic, bilabiate flowers; usually 4 didynamous stamens.
6. Superior, 4-lobed ovary with gynobasic style; fruit of four nutlets.
Exam focus: learn the diagnostic character
combination.

Important Genera
Ocimum — basil and tulsi; aromatic herbs rich in essential oils.
Mentha — mints; important source of menthol and flavouring oils.
Salvia — sages; diverse flowers and specialized pollination mechanisms.
Leucas — common herbs of South Asia, including L. aspera.
Pogostemon — patchouli and related aromatic taxa.
Other important genera include Thymus, Rosmarinus (historical name), Lavandula and Origanum.

Important Species
Ocimum tenuiflorum — Tulsi / Holy basil; medicinal and cultural importance.
Ocimum basilicum — Sweet basil; culinary and essential-oil use.
Mentha arvensis — Field mint; menthol-rich oil source.
Mentha × piperita — Peppermint; flavouring and pharmaceutical use.
Salvia officinalis — Common sage; culinary and medicinal use.
Pogostemon cablin — Patchouli; perfumery and fragrance industry.

Medicinal Importance
Ocimum spp.: traditional use in respiratory, digestive and inflammatory complaints.
Mentha spp.: carminative, cooling and flavouring applications; menthol is widely used.
Salvia spp.: traditional applications and culinary use; rich in phenolics and volatile constituents.
Thymus and Origanum: aromatic herbs with thymol/carvacrol-rich oils.
Pharmacological activities reported for Lamiaceae plants include antioxidant, antimicrobial and anti-
inflammatory effects; activity depends on species, extract and dose.

Essential Oils & Phytochemicals
Essential oils are commonly stored in glandular trichomes.
Major compounds across the family include menthol, thymol, carvacrol, eugenol, linalool and rosmarinic
acid.
Chemical profiles vary with species, genotype, plant part, climate and extraction method.
Essential oils support applications in food, fragrance, cosmetics and research on bioactivity.

Economic Importance
Food & spices: basil, mint, oregano, thyme and sage.
Perfumery: lavender and patchouli oils.
Pharmaceuticals: menthol, herbal preparations and aromatic formulations.
Cosmetics: fragrances, oral-care products and topical preparations.
Ornamentals: lavender, coleus and many aromatic garden plants.
Agriculture and beekeeping: many species are valuable nectar sources.

Traditional Medicine
Lamiaceae has a long history in Ayurveda and other traditional health systems.
Tulsi, mint, thyme-like herbs and other aromatic species are used in household remedies.
Common traditional preparations include infusions, decoctions, fresh leaves and essential oils.
Traditional use should be distinguished from clinically established efficacy and standardized dosing.

Taxonomic Significance & Comparisons
Lamiaceae is placed in Lamiales and shows close historical comparisons with Verbenaceae.
Lamiaceae is strongly characterized by a 4-lobed ovary and gynobasic style.
Traditional diagnostic combinations also include opposite leaves, bilabiate corolla and didynamous stamens.
Modern molecular phylogenetics has reshaped generic boundaries and placement of some former
Labiatae/Verbenaceae taxa.

Lamiaceae vs Verbenaceae
Leaf arrangement: Lamiaceae usually opposite; Verbenaceae may be opposite, whorled or alternate
depending on lineage.
Stem: quadrangular stems are common in Lamiaceae but not diagnostic for Verbenaceae.
Style: gynobasic in Lamiaceae; terminal style is typical in Verbenaceae.
Ovary: deeply 4-lobed in Lamiaceae; commonly less deeply divided in many Verbenaceae.
Fruit: four nutlets are typical of Lamiaceae; fruit forms vary more broadly in Verbenaceae.

Summary & Key Take-Home Points
Lamiaceae is a major aromatic family of Lamiales.
Look for the combination: opposite leaves + often quadrangular stem + bilabiate flower + 4-lobed ovary +
gynobasic style + four nutlets.
Verticillaster is a characteristic inflorescence pattern in many members.
Family members are major sources of culinary herbs, essential oils, medicinal plants and fragrance materials.

MSc-Level MCQs & Discussion
1. Which feature best identifies Lamiaceae? A) Inferior ovary B) Gynobasic style C) Epigynous flowers D)
Tetradynamous stamens
2. Verticillaster is best interpreted as: A) True whorl B) Condensed cymose cluster C) Raceme D) Umbel
3. Typical Lamiaceae fruit consists of: A) Capsule B) Berry C) Four nutlets D) Drupe
4. Didynamous stamens mean: A) 2 equal B) 4 equal C) 4 in two unequal pairs D) 6 in two whorls
5. Why is the ovary described as 4-lobed? Explain its development from the bicarpellary gynoecium.
6. Compare Lamiaceae and Verbenaceae using three diagnostic characters.

Lamiaceae family full discription slide.pptx

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