Botany - B.E. Yakubenko 2017

Part Three. The Plant Kingdom (Plantae)
Chapter IX. Division Angiosperms, or Flowering Plants (Angiospermae, Magnoliophyta)
Laboratory Session Topic 14.54. Water-plantain family (Alismataceae)

General Remarks. The Alismataceae family comprises mostly herbaceous, perennial, aquatic, or marsh plants, typically with a leafless stem and petiolate (in terrestrial forms) elliptic, oval, lanceolate, linear, sagittate, or ovate leaves gathered in a basal rosette. The inflorescence is a panicle. Flowers are bisexual or unisexual, actinomorphic, with a six-part perianth consisting of three outer, usually green, and three inner, petal-like segments. Stamens six to numerous, free or connate at the base; Ovary superior. Fruits are aggregateachenes or follicles.

When examining Representatives of the family, attention should be paid to the floral Structure—which may be bisexual or unisexual—the number of stamens and pistils, and the fruit type. An important diagnostic feature is the shape of the leaf blade.

Objects:

1. Water plantain (Alisma plantago-aquatica L.)

2. Common arrowhead (Sagittaria sagittifolia L.)

Tasks:

1. Familiarize yourself with The Diversity of plants belonging to the Alismataceae family, perform a written morphological analysis, and identify the plants.

2. Carry out the morphological analysis and plant identification using The Water Plantain as an example.

3. Study the CHARACTERISTICS OF THE Alismataceae family.

Equipment and Materials: live, fixed, or herbarium handout material, hand lenses, dissecting needles, Microscope slides, tweezers, charts, identification keys.

Macroscopic Studies of water plantain (Alisma plantago-aquatica L.). An herbaceous, rhizomatous, perennial plant growing in the littoral zone of water bodies, along waterlogged meadows, and in grassy and sedge bogs. Rhizome tuberous, up to 2 cm in diameter, with adventitious roots up to 25 cm long. Lower submersed leaves sessile, elliptic, while emersed leaves are long-petiolate, ovate. Inflorescence a whorled-branched pyramidal panicle, consisting of 5–6 whorls with 6–9 branches per whorl. Pedicels long, slender. Flowers bisexual, actinomorphic, perianth double, sepals three, green, corolla three-petaled, petals with rounded apices, white or pale pink, with a yellow base. Stamens six. Pistils numerous, arranged in a whorl, with a style on the ventral side. Ovary superior. Fruits are aggregate achenes. Floral formula: *Ca₃Co₃A₆G_∞;

Other species are described and identified following the same scheme.

Conclusion. Alismataceae are perennial aquatic-palustrine or marsh-meadow and emergent aquatic plants possessing roots. Leaves are mostly petiolate, forming a basal rosette. Flowers are bisexual or unisexual, actinomorphic, with a double, trimerous perianth. Stamens and pistils number six or are numerous. Ovary superior. Fruits are aggregate achenes or follicles. These plants are used as fodder, food, ornamentals, and medicinal herbs; under mass proliferation, they can cause the overgrowth and siltation of water bodies.

Class="center">Self-Assessment Questions

1. What life forms are represented by plants of the Alismataceae family?

2. What ecological group do the Alismataceae belong to?

3. What type of leaves do plants in the Alismataceae family have?

4. How are the flowers arranged in Alismataceae?

5. What is the floral formula in Hydrocharitaceae?

6. Which Alismataceae species are classified as aquatic ornamental plants?