Plant Notes Part 2
Gymnosperms • The most ancient surviving seed plants are the gymnosperms (“naked seeds”). • These include cycads, gnetophytes, ginkgoes and conifers, which are the most common of the cone-bearing plants.
Gymnosperms • Conifers thrive in a wide variety of habitats and have leaves that are long and thin (like pine needles) with thick, waxy coverings because they have adapted to dry conditions in order to conserve water.
Angiosperms • Flowering plants originated on land about 135 million years ago & soon dominated plant life. • Angiosperms (“enclosed seed”) developed unique reproductive organs known as flowers, which are an evolutionary advantage because they attract pollinators like bees, butterflies and birds, which in turn get food and then transport the pollen to other flowers.
Angiosperms • Flowers contain ovaries, which surround and protect the seeds & give angiosperms their name. • After pollination, the ovary develops into a fruit, which protects the seed and aids in dispersal when animals eat the fruit & then excrete the seeds far away from the plants’ original location.
How Angiosperms are Classified: Monocots v. Dicots • Monocots and dicots are types of angiosperms that are named for the number of seed leaves (cotyledons) in their plant embryo. • Monocots have one seed leaf, while dicots have two. (mono = 1, di = 2)
Monocots v. Dicots MONOCOTS: Parallel venation DICOTS: Netted venation
Monocot or Dicot? How you can tell: • # petals? 5 • Venation? Netted
Monocot or Dicot? • How you can tell: • # petals? 6 • Venation? Parallel
Monocot or Dicot? • How you can tell: • # petals? N/A • Venation? Parallel
Monocot or Dicot? • How you can tell: • # petals? 5 • Venation? Netted
Woody v. Herbaceous Plants • Woody plants are made primarily of cells with thick cell walls that support the plant body and include trees, shrubs and vines. • Ex. Roses & grapes
Woody v. Herbaceous Plants • Plant stems that are smooth and non-woody are characterized as herbaceous plants, which don’t produce wood as they grow. • Ex. Sunflowers
Three Types of Plants • If you’ve ever planted a garden, you know that many flowering plants grow, flower and die in a single year. Other types of plants continue to grow from year to year. • There are 3 categories of plant life spans: • Annuals • Biennials • Perennials
Annuals • Complete their life cycle in 1 growing season
Biennials • Complete their life cycle in 2 growing seasons
Perennials • Live from one growing season to another, usually for many years. • Ex. Trees & grass