Questions and Answers
What type of growth habit do most Alismataceae species exhibit?
Which genera of Alismataceae includes the highest number of species?
What is the common feature of the leaves in Alismataceae?
What type of flowers do Alismataceae typically produce?
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How is the gynoecium of Alismataceae characterized?
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What term is used to describe the arrangement of Alismataceae stamens?
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What is a key anatomical feature of Alismataceae stems?
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What type of fruit do Alismataceae produce?
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Which of the following genera has the smallest number of species?
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What type of leaf arrangement is characteristic of the genera mentioned?
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What type of fruit do members of this family typically produce?
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Which of the following statements about the perianth is correct?
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How is the gynoecium structured in the genera discussed?
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Which feature correctly describes the stamens in these genera?
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What is a common feature of the inflorescence in some genera like Amomum?
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Which of the following genera is primarily known for being ornamental?
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Study Notes
Family Overview
- Comprises 18 genera and approximately 120 species, including Limnocharitaceae.
- Worldwide distribution with a strong presence in northern temperate regions.
Salient Features
- Includes aquatic or marsh plants.
- Possesses laticifers for latex production.
- Leaves are petiolate with a well-developed blade.
- Inflorescence is scapigerous.
- Perianth consists of two whorls, differentiated into sepals and petals.
- Stamens range from 6 to many, carpels also vary from 6 to many and are free.
- Typically one ovule per carpel; fruit is an etaerio of achenes.
- Embryos are characterized as curved.
Major Genera
- Echinodorus: 35 species.
- Sagittaria: 25 species.
- Alisma: 9 species.
- Burnatia: 3 species.
Habit & Habitat
- Plants are primarily perennial, with some annual or polygamous forms (like Burnatia).
- Grow in floating or emergent forms, classified as aerenchymatous.
- Found in aquatic or marsh environments.
Stem Characteristics
- Stems can be corms or rhizomes.
- Contain secretory cavities that produce latex.
- Lacks secondary thickening.
Leaf Structure
- Leaves exhibit basal aggregation and are typically simple and petiolate (sheltering is rare).
- Spiral arrangement, often dimorphic: juvenile leaves are usually linear, adult leaves may be linear, ovate, triangular, sagittate, or hastate.
- Venation can be parallel or reticulate.
- Stomata types include paracytic or tetracytic (rare occurrence).
Inflorescence Types
- Configured as a scapose raceme or panicle, occasionally resembling an umbel.
- Flowers may be whorled or solitary; spathe is absent.
Flower Characteristics
- Can be bisexual or unisexual; actinomorphic in shape.
- Typically subsessile to pedicellate, bracteate, and hypogynous.
- The receptacle can be flat, expanded, or convex.
Perianth Details
- Arranged in biseriate and dichlamydeous forms, trimerous, and lacks a hypanthium.
- Composed of three aposepalous sepals in the calyx and three apopetalous, caducous petals in the corolla.
Stamens Structure
- Variable between 6, 9, or many and arranged in whorls.
- Can be distinct and free or connate in bundles.
- Anthers are longitudinal and may dehisce in an extrorse or latrorse manner.
Gynoecium Details
- Apocarpous structure with a superior ovary composed of multiple carpels (3 to many).
- One terminal style and stigma; placentation is predominantly basal (rarely marginal).
- Ovules can be anatropous or campylotropous, bitegmic, and occur in numbers of one to many per carpel.
Fruit Characteristics
- Fruits can be aggregates of achenes or basally dehiscing follicles.
- Seeds are exalbuminous, indicating a lack of endosperm.
Major Genera
- Alpinia - 165 species
- Amomum - 130 species
- Zingiber - 95 species
- Globba - 65 species
- Curcuma - 55 species
- Kaempheria - 65 species
- Hedychium - 66 species
Family Description
- Consists of perennial herbs with tuberous roots.
- Plants are aromatic, containing etherial oils, terpenes, and phenyl-propanoid compounds.
- Aerial stems are generally short, leafless, and rarely foliate.
Stem Characteristics
- Stems are rhizomatous and exhibit a sympodial growth pattern.
Leaf Structure
- Leaves are distichous (arranged in two rows), simple, and sheathing.
- Sheaths often form a pseudo-stem; petioles are present.
- Leaves are usually ligulate with penni-parallel venation and contain a pulvinus in Zingiber.
Inflorescence Types
- Appears as bracteate spikes (Amomum), racemes, thyrses, or solitary flowers (Monocostus).
- Some inflorescences have an involucre (Geanthus), while others do not (Gastrochilus, Amomum).
Flower Characteristics
- Flowers are bisexual, zygomorphic, bracteate, and epigynous.
- Perianth is biseriate, made up of differentiated sepals and petals.
Perianth Details
- Composed of 3 green sepals that are connate into a tube.
- 3 petals are showy; the posterior petal is often enlarged and somewhat united.
Reproductive Structures
- Stamens: 1 fertile (median posterior); characterized by longitudinal anther dehiscence and are dithecal.
- Staminodes: 4 petaloid, with two in the inner whorl connate, forming a labellum; the third member of the outer whorl is absent.
Gynoecium Features
- Syncarpous with an inferior ovary comprised of 3 carpels (median carpel is anterior).
- Can have 1 or 3 locules; the style is terminal with axile or parietal placentation.
- Ovules are anatropous, bitegmic, and numerous per carpel; septal nectaries are absent, replaced by two epigynous nectaries.
Fruit Description
- Fruits can be dry or fleshy, either loculicidal or indehiscent capsules.
- Seeds are arillate with starch-rich endosperm and perisperm.
Pollination
- Insect-pollinated, which aids in reproductive success.
Economic Importance
- Many species serve as ornamentals, including Hedychium (ginger lily), Kaempheria, Costus, Nicolaia (torch ginger), and Alpinia.
- Important spices include rhizome-derived products such as
- Zingiber officinale (ginger, Adrak)
- Curcuma longa (turmeric, Haldi)
- Amomum subulatum (Bengal cardamom)
- Elettaria cardamomum (Malabar cardamom).
- East Indian arrowroot from Curcuma angustifolia tubers, perfumed powder (abir) from Hedychium spicatum rhizomes.
- Spice Melegueta pepper extracted from Aframomum melegueta.
- Rhizomes of Alpinia zedoaria used for spice, tonics, and perfumes (zeodary), while A. galanga is utilized in medicine and flavoring (galangal).
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Description
Explore the diverse family of Alismataceae, comprising 18 genera and approximately 120 species, with a focus on their distribution and key features. Learn about their aquatic or marsh plant characteristics, reproductive structures, and major genera such as Echinodorus and Sagittaria.
