Characteristics and economic importance of Liliaceae (Lily family)

1. Diagnostic features

• Mostly perennial herbs, small shrubs or sometimes climbers.
• Stem usually modified into bulbs, corms or rhizomes.
• Leaves radical or cauline, alternate or whorled.
• Inflorescence racemose, borne on long leafless scape.
• Flower small, bracteates bisexual, actinomorphic, hypogynous, trimerous.
• Tepal-6 in two whorls.
• Stamens 6 in two whorls, polyandrous, epipetalous.
• Gynoecium tricarpellary, syncarpous, trilocular, ovary superior, ovules numerous.
• Placentation axile.
• Fruit usually a capsule or sometimes berry.

2. Distribution

• Cosmopolitan distribution.
• Mostly in warm temperate and tropical regions of the world.

3. Vegetative characters

a) Habit

• Mostly perennial herbs, rarely shrubs and trees (Dracaena, Yucca).
• The herbaceous members perenneate with the help of bulb (Allium), rhizome (Polygonatum) or corms (Colchicum).
• Some species grow growing in xerophytic conditions are Aloe, Agave,Yucca, etc.

b) Root

• Adventitious root system.
• Sometimes thickened a tuberous to store food (Asparagus).

c) Stem

• May be aerial or underground.
• Aerial stems are erect or climbing (Gloriosa, Smilax), branched- branches modified  into needle-like cladodes in Asparagus.
• Underground stem is modified into bulb (Allium), rhizome (Polygonatum), or corm (Colchicum).
• In some cases the stem shows secondary growth and become woody in Aloe, Yucca, Dracaena.

d) Leaves

• Radical or cauline and ramal in Dracaena.
• Simple, exstipulate or stipulate, usually alternate, sometimes opposite (Scolypous) or whorled (Trillium).
• Usually sessile with sheathing leaf base.
• Venation parallel while reticulate in Smilax and Paris.
• The leaves are thick and succulent with spiny apex and margin (Aloe), scale like in Asparagus and Ruscus.
• The leaf tips are modified into tendrils in Gloriosa.
• Leaves are cylindrical in Allium.
• Only two leaves are present in Erythronium.
• Leaves are absent in Bowiea.

Image source: braincart

4. Floral characters

a) Inflorescence

• Usually racemose- simple raceme (Aloe), terminal panicle (Yucca), umbel, spadix (Rhodea).
• Sometimes solitary terminal (Tulipa), solitary axillary (Gloriosa), condensed cyme (Allium), borne on a long leafless scape.

b) Flowers

• Bracteate, complete, bisexual or rarely unisexual.
• Actinomorphic, sometimes zygomorphic (Howarthia), trimerous, rarely dimerous (Mainthemum), tetramerous (Aspidistra), hypogynous.

c) Perianth

• Tepals-6, in two whorls (3+3).
• Usually gamopetalous or polypetalous (Lilium), rarely 8 (4+4) in Paris or 4 (2+2) in Mainthemum.
• Perianth tubular or campanulate (Aloe), bilabiate in Howarthia, usually petaloid.
• Sometimes sepaloid or differentiated into calyx and corolla (Trillium).
• Aestivation valvate or imbricate.

Image source: qsstudy

d) Androecium

• Stamens usually 6 in two whorls (3+3), rarely 4 in Mainthemum, 3 in Ruscus, 8 in Paris or 9-12 in Tofieldia.
• polyandrous or rarely monadelphous (Ruscus), usually opposite to the tepals, epitepalous.
• Anthers 2-celled, basifixed or versatile, dehiscing by longitudinall slits or rarely by a terminal pore.
• The filaments are very short (Ophopgon), filiform i.e thread like in Asphodeelus, anthers extrose or introse.

e) Gynoecium

• Usually tri-carpellary, syncarpous.
• Rarely 2 in Mainthemum, trilocular with many ovules in each locule.
• Placentation axile, ovary superior.
• Style simple and stigma trilobed.

f) Fruit

• Usually a capsule (Aloe, Gloriosa) or a berry (Asparagus).

g) Seed

• Endospermic, embryo small.

h) General floral formula

Economic importance

i) Food

• Allium cepa (onion), A. sativum (garlic), young fleshy shoots of Asparagus officinalis and tuberous roots of A. racemosus are used as vegetable.

ii) Medicine

• ‘Aloin ‘ is obtained from Aloe africana and A. barbedensis (Ghiukumari) used as laxative.
• The bulblets of garlic are used as antiseptic.
• Leaves of Aloe vera provide mucilaginous liquid used in piles and inflammation.
• Raw Allium cepa is used as in constipation, diarrhoea and cholera.

iii) Flavours

• Bulbs of Allium cepa and A. sativum and the roots of various species of Smilax are used as flavouring agents.

iv) Chemicals

• Colchicine is obtained from Colchicum luteum, which is used to induce polyploidy.

v) Resin

• Dracaena provides a resinous juice, the dragon’s blood (D. cinnabari) is used in varnished and dyes.
• The leaves of Xanthorrhoea provide an acrid resin, which is used for making sealing wax, spirit, varnishes for coating metals.

vi) Fibres

• Phormium Texan (Flax), Yucca filamentosa (ketuke), Smilax glabra give excellent fibres.
• These fibres are used for cordage, fishing nets, mattings, twines , etc.

vii) Ornamental plants

• Asparagus, Agapanthus africanus, Gloriosa superba, Lilium candidum, Ruscus aculeatus, etc are well known garden plants.

References: 

i) https://www.biologydiscussion.com/botany/monocotyledons/liliaceae-characters-distribution-and-types/48562

ii) https://www.first-learn.com/liliaceae-family-plants.html

Characteristics and economic importance of Liliaceae (Lily family)