BIOL 320 — Lecture (Unit 2)
Asteraceae
- Sunflower family
- Composite
- Annual to trees
- Variable leaves
- Inflorescent head
Radiate Heads
- Receptacles
- Bracts on the receptacle: Phyllaries/Involucre
- Ray and disk flowers
- Ovary attached to a large receptacle
- Modified sepal: Pappus
- Bracts around the disk flowers: paleae (sing. palea)
- Disk flowers are bisexual, male, or sterile
- Plunger-style
- Stamens are adnate to corolla
- 2 style branches push out and hook outside of an antheridial tube
- Ray flowers are female or sterile
- Three lobes
- Made from five fused petals
- Inferior ovary with 2 fused carpels
- Achenes
- Corolla of 5/4 connate petals
- Radiate heads: Ray flowers and disk flowers are present
- Different types of pappus:
- None (Epappose) or a lot
- Bristled: Long, pointed, flexible
- Barbed awns: Inflexible
- Scales: Flat
- Plumose: Typically bristles; feathered or fluffy
- Original bristle has side bristles that make it appear plumose
- Tufts of bristles
- Sunflowers
Liguliflorous Heads
- Ligulate flowers only
- Bisexual flowers
- Bilateral
- Ligule strap
- Dandelions
- Five lobes
Discoid Heads
- Many species in Senecio
- Only disk flowers
Senecio (Packera)
- Cyme-like inflorescence clusters
- Determinate inflorescence
- End flowers open and buds are near base of stem
- 1 main series of phyllaries
- 8, 13, or 21 phyllaries in a series
- may be black-tipped
- Epaleate
- Minute barbed bristle pappus
- Generally yellow flowers
Senecio vulgaris
- Butterweed, common Senecio, common groundsel
- Weed
- Short outer phyllaries
- Cobweb hairs/trichomes
- Alternate leaves
Poaceae
- Grass family
- Gramineae
- Most are herbaceous, non-woody
- Annuals to perennials
- Cereal crops: Corn, rice, oats, wheat
- Monocots
- Fibrous roots
- Swollen nodes and hollow internodes
- Dominates low-rainfall landscape
- Vegetative
- Two growth forms
- Rhizomatous growth form/Sod-forming grasses
- Bunch grasses
- Most native Californian grasses
- Linear leaves with a sheath and a blade
- Open sheathes are non-fused and wrapping/overlapping around the stem
- Vs. Fused sheathes which are fused directly to stem
- Leaves have a ligule between the blade and sheath: Flap of fibrous tissue
- Ligules are used in grass identification
- Inflorescences may be spike-like or open
- Florets: A basic unit in inflorescence with a flower and two ranked bracts
- Lemma is inferior bract, palea is superior to other bract
- Bracts enclose the flower
- Lemma possesses awms: fibrous filaments that are terminal are close to the terminal
- Spikelet: The basic unit of inflorescences; one or more florets with two ranked bracts
- Bracts are referred to as “glumes”
- Flowers are not showy, wind-pollinated
- 3 stamens
- Dangling, hanging out of inflorescence
- Superior ovary made of 2 fused carpels (connation)
- Remnants of perianth: Lodicule glands
- May swell to open the flower
- Feathery stigmas for catching pollen
Avena
- Oats
- Four species; all non-native
- Annuals
- Ligule is membranous and rounded at top; 2-5mm (large)
- Inflorescence is panicle-like
- Spikelets hang down (pendant) at maturity
- Awm is from back-middle side of lemma
- Lemma tip has two membranous forks; awm is attached just beneath tip
- Spikelets are laterally compressed vs. dorsally compressed
Avena fatua
Festuca perennis
- Rye grass
- Non-native
- Spike-like inflorescence
- 1 glume on outside of spikelet
- Sessile spikelet
- Multiple florets laterally compressed (~10) and two-ranked
- Awms on tips of lemmae; variable lengths
Bromus
- Brome, chess
- Some species are native
- Panicle-like or spike-like
- Glumes are less than width of the lower floret
- Lemma is two-forked and has a lengthy awn attached behind the tip
Bromus diandrus
- Ripgut brome grass
- Panicle-like inflorescence
- Long awm attached to lemma
- Abrasive