Family – Rutaceae

Scientific Classification

Diagnostic Features of Rutaceae

Rutaceae consists of trees, shrubs, and occasionally herbs. These plants are common in tropical and subtropical regions, especially abundant in South Africa and Australia, which are major centers of diversity.

Examples:

• Trees: Aegle marmelos (Bael), Chloroxylon swietenia
• Shrubs: Citrus species (lemon, orange), Murraya species (kamini)
• Rarely herbs: Ruta graveolens
• Climbers: Parmignea griffithai (woody climber using thorns), Todalia (armed with rose-like thorns)

Vegetative Characters

• Root: Taproot, branched
• Stem: Aerial, erect, cylindrical, solid, branched, woody, often spiny

Leaves

• Alternate (rarely opposite, as in Evodia)
• Simple (e.g., Diosma) or compound (e.g., Aegle, Feronia)
• Pinnately compound with 3 to many leaflets
• In Citrus, petiole is winged, with a distinct joint at the top forming a leaf-like structure — hence, leaves are considered palmately compound with reduced lateral leaflets
• Thorns are modified leaves

Special Feature of Leaves:

• Oil glands: Present throughout leaf blade
• Visible as translucent dots
• When crushed, the characteristic aroma indicates essential oils
• Oil cavities are lysigenous (formed by cell dissolution)

Floral Characters

Inflorescence

• Typically cymose
• Feronia: racemose
• Correa, Citrus: solitary axillary
• Ruta: dichasial cyme — central flower pentamerous, lateral tetramerous

Flowers

• Actinomorphic (radially symmetrical)
• Bisexual (mostly)
• Pentamerous
• Bracteate and bracteolate
• Hypogynous, cyclic
• Disc present below ovary
• All floral parts contain oil glands

Exceptions:

1. Some genera (Dictamnus, Casparia) show zygomorphy (bilateral symmetry).
2. Flowers unisexual in Zanthoxylum, Todalia, Evodia; both bisexual and unisexual flowers found in Feronia.
3. Triphasia flowers are trimerous; Ruta lateral flowers are tetramerous.
4. Pleiocarpum has perigynous or epigynous flowers.

Calyx (Sepals)

• Free (e.g., Ruta) or fused (e.g., Correa)
• Arrangement: imbricate (quincuncial)
• Usually 5 (sometimes 4 or 3)
• Green in color

Corolla (Petals)

• Usually free; in Correa and Casparia, petals are fused
• Petal arrangement: twisted or imbricate
• Number: 3, 4, or 5
• Color: white or yellow

Androecium (Stamens)

• Usually 10, in two whorls of 5 each
  • Outer stamens opposite petals
  • Inner stamens opposite sepals → Obdiplostemonous
• May be:
  • 8 (4+4) in Ruta
  • 6 (3+3) in Triphasia
• In Citrus, stamens are numerous and grouped in bundles (polyandrous condition)
• Anthers: dithecous, introrse, dehiscing longitudinally

Gynoecium (Carpels)

• Number of carpels: 3 to 5 (rarely 2 or many, e.g., in Citrus)
• Carpels are syncarpous but easily countable
• Ovary superior, lobed
• Each locule contains 2 ovules
• Placentation: axile
• Disc present below ovary
• Stigma lobed, style simple

Fruit

Depends on fusion of carpels:

• Dictamnus, Ruta: schizocarpic fruit (splits into parts)
• Aegle, Feronia: amphisaraca – hard rind, edible pulp
• Citrus: hesperidium – modified berry with:
  • Exocarp (outer peel): leathery
  • Mesocarp: spongy white
  • Endocarp: membranous sacs with juice vesicles (edible)

Other Fruit Types:

• Ptelea: samara (winged indehiscent fruit)
• Flindersia: capsule

Seeds

• In Citrus: no endosperm; presence of multiple embryos (up to 13)
• In others like Zanthoxylum, Boronia: seeds may have endosperm
• Embryos in Citrus arise from nucellus (adventive embryony)

Habit

• Evergreen large shrubs or small trees

Root

• Taproot

Stem

• Erect, aerial, woody, green

Leaves

• Alternate, compound (3–7 leaflets), petiolate, with reticulate venation

Inflorescence

• Axillary or terminal cymes

Flowers

• Pentamerous, white, fragrant

Floral Formula

⊕ ⚥ K₅ C₅ A₅˖₅ G(2-3)

Economic Importance of Rutaceae

The Rutaceae family holds immense economic value, primarily due to its fruit-bearing species rich in Vitamin C, essential oils, and ornamental use.

Major Citrus Fruits (Genus: Citrus)

1. Citrus aurantifolia – Kagzi lime
2. Citrus limon – Big lemon
3. Citrus aurantium – Sour orange
4. Citrus limettoides – Sweet lime
5. Citrus reticulata – Mandarin orange
6. Citrus sinensis – Sweet orange (Mosambi)
7. Citrus maxima – Pomelo (Chakotra)

All Citrus fruits are vitamin C rich, consumed fresh, juiced, or preserved.

Other Economically Important Plants in Rutaceae

8. Aegle marmelos (Bael) – Sacred to Lord Shiva; pulp used in digestive remedies
9. Feronia limonia (Wood Apple) – Pulp used to make chutneys or eaten raw
10. Murraya koenigii (Curry Leaf Tree) – Leaves used in Indian cuisine for aroma
11. Murraya paniculata (Kamini) – Grown for fragrant flowers in gardens
12. Glycosmis pentaphylla – Fruits edible; branches used for chewing sticks
13. Zanthoxylum alatum – Spicy fruits used like pepper; stems used for walking sticks
14. Ruta graveolens – Medicinal plant; dried leaves used in traditional remedies
15. Chloroxylon swietenia – Premium timber for furniture and veneers
16. Choisya ternata – Ornamental plant for beautiful foliage and flowers (cooler climates like Ooty, Shimla)
17. Luvanga scandens – Woody climbing shrub with white fragrant flowers, found in Assam and West Bengal

Read Also: Family – Rubiaceae: Characteristics, Classification, and Economic Importance

Conclusion

The Rutaceae family is botanically diverse and economically vital. From essential oil-rich leaves to nutritious and aromatic fruits, this family holds a strong place in agriculture, medicine, culinary use, and ornamental gardening. Notably, Citrus species form the backbone of tropical fruit industries, while several other Rutaceae members contribute to medicinal products, timber, and garden aesthetics.