NOTES November 11

• Division Magnoliophyta (flowering plants…= angiosperms)
• Class Liliopsida (monocots)
• Subclass Commelinidae (includes 7 orders, see p. 435 Walters & Keil)
• Order Cyperales (Includes Cyperaceae and Poaceae)
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• Stems (culms) generally triangular, sometimes obscurely so
• Stems generally solid at maturity (tissue includes "ground" tissue and scattered strands of vascular tissue)
• Leaves generally in three "ranks"
• Leaves: sheath and blade. Sheath margins are completely fused, therefore the sheath completely embraces the stem. If you try to pull the sheath away from the stem, it will tear. Compare this situation to that in grasses.
• Flowers:
       - Very small
       - Perfect or imperfect, depending on the species
       - Many species are monoecious, with male flowers and female flowers in separate places
       - Flowers are clustered into spikelets
       - Spikelets may be secondarily arranged as spikes, panicles, umbels
       - In a spikelet, each flower is subtended by a scale
       - Scales may be distichous or spiral arranged
  
• Gynoecium:
       - a single compound pistil in female (or in perfect) flowers, made up of either 2 or 3 carpels, depending on the species
       - mature ovary (fruit) is an achene
• Carex      - Very large genus, many hundreds of species
       - Female flowers surrounded by a bag-like structure called perigynium (= "around ovary"). Plural of perigynium is "perigynia"
       - Stigmas (s=either 2 or 3) poke out of the opening at the top, able to receive pollen
• Rhynchospora (name means "beak seed")
       - Very large genus
       - Ovary retains the style at maturity, which is present as a "beak", and often very diagnostic in separating species