sc: asteridae order: asterales family: asteraceae “composites, sunflowers” 1. 22,000 species in...
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SC: Asteridae Order: Asterales Family: Asteraceae “Composites, Sunflowers”
1. 22,000 species in 900 genera 2. Flowers (florets) are typically arranged in HEADS. Expanded
Receptacle; florets epigynous; entire Head surrounded by an involucre of bracts – phyllaries; head is support by a flower stalk called the peduncle; inferior
Pappus – bristles or scales (modified calyx) Corolla – coalescence of petals Stamen – 5 coalescent around style Pistil – one; 2 stigma lobes
SC: Asteridae Order: Asterales Family: Asteraceae “Composites, Sunflowers”
Pappus – bristles or scales (modified calyx)
Corolla – coalescence of petals
Stamen – 5 coalescent around style
Pistil – one; 2 stigma lobes
3. Ray Flowers – 3 of the coalesced petals elongate into a ligule.
4. Great variablity! Sterile, pistilate, staminate, perfect….
Tribes Chicory Tribe –
1. Ray flowers only 2. Milky sap
Lactuca “wild lettuce”, Taraxicum “dandelion”, Chicorium “chicory”
Tribes Ragweed Tribe -
Monoecious; staminate and pistillate flowers on same plant
Ambrosia trifida “giant ragweed”, Ambrosia artemisifolia “small ragweed”
Tribes Aster Tribe -
Style branches flattened in middle….
Solidago “goldenrods”, Aster “asters”
Tribes Sunflower Tribe -
1. Both disc and ray flowers
2. Usually a crown of hairs at base of stigma
3. Pappus mostly bristle-like
Helianthus “sunflowers”, Chrysanthemum “ox-eyed daisy”
Tribes Snakeroot Tribe -
1. disc flowers only 2. leaves mostly
opposite
Eupatorium rugosum “white snakeroot”, Liatris “blazing star”, Eupatorium purpureum “Joe Pye weed”, Eupatorium altissimum “tall thoroughwort”
Tribes Ironweed Tribe –
1. Disc flowers only 2. Anthers sagittate 3. Stigma lobes long
and pointed
Veronia “ironweed”
Tribes Thistle Tribe –
Receptacle with a spiny involucre of bracts
Cirsium vulgare “bull thistle”, Carduus nutans “musk thistle”