Lecture 5- Proteceae and Legumes Flashcards
What is the composition of the Australian flora?
-bryophytes= 1847 -fern and allies= 498 -gymnosperms= 120 -flowering plants= 21 000
What are the four families of plants we are looking at?
- Myrtaceae 2. Fabeceae 3. Mimosaceae 4. Proteaceae -they are among the largest families in Australia
What are the characteristics of the family Proteacae?
-1500 species (800 species in Australia= centre of diversity) -forests, woodlands, heathlands on low nutrient soils (Banksia, Grevillea) -named by Linnaeus -largely southern hemsiphere distribution, present prior to breakup of Godnwana (and that is why its distribution is like that) -most common in drier heathlands and woodlands, some also in rainforests -features to deal with dry, fire environment -sclerophyll woody shrubs and trees with corky bark, often lignotubers -fruits woody follicles or fleshy drupes
How old is Proteaceae family?
-Old Gondwanan family with fossil pollen 80 million years old (Cretaceous) -DNA sequencing places family as an early evolutionary line of flowering plants
What is the morphology of a typical flower?
- typical flower morphology
- sepals= often green, leaf-like, as flower buds the sepals surround the developing flower and protect the tissue underneath
- petal= commonly colourflow and showy, function= part of the floral display, visual cue for pollinators
- petals and sepals= perianth, the sterile part of the flower
What does the typical Proteaceae flower?
-e.g. Grevillea -4-lobed perianth (tepals) -4 stamens attached to tepals -ovary 1 or 2 compartments -style long and acts as pollen presenter (male phase) then receives pollen (female phase) -don’t have separate perianthal layers= called undifferentiated perianth= tepals
What are flowers like in Grevillea (Proteaceae family) flowers?
- all of the reproductive structures will be curved in the perianth
- then become more straight
- then flowers fully open extend
- style and stigma in bud is directly against the anthers
- male phase= the anthers release pollen when flower is young before fully extending
- so the pollen can be deposited on the stigma and style = there it functions as the secondary pollen presenter
- perianth (tepals) have lobes at the end -nectary gland below the ovary secretes nectar
- stamens don’t have the filament, only have anther
How does pollination work in the Grevillea (Proteaceae)?
-secondary colour presentation=deposition of pollen on pollinating animals doesn’t happen directly from the anthers -by another organ -the style and stigma= function as pollen presenter -anther is attached on the inner surface of the tepal -the bird has long bill and tongue = special feathery and sucking at nectar -it can come in contact with the pollen presenter, can be hit on the head by the stigma -distinct male and female phase, when in male, stigma not receptive, -after all pollen removed they go into female phase, then stigma is receptive and the honeyeaters can bring the pollen in -pollination in gravillias= look it up
How does a Banksia (belongs to the Proteaceae) flower open?
-from the bottom upwards
How are Banksia flowers adapted to being pollinated by birds?
-Small flowers clustered in an inflorescence Attracts pollinators and provides landing platform -stout structure= more visible -need somewhere to perch while it feeds -red colour attracts birds
What are the main bird pollinators?
-birds really important for plants -honeyeaters, family Meliphagidae -circa 75 species -specialist nectar feeders -highly evolved co-evolutionary relationships
What is the mammal that is a pollinator of the Banksias (Proteaceae)?
-honey possum= a mojor pollinator for banksias -specialist nectar feeder, specialised tongue= highly divided at the end= good for sucking up nectar
What are the fruits and seeds like in Banksias?
- Often only a few ovaries develop as fruits
- Fruit a woody follicle, usually opens after fire
- 2 winged seeds per follicle
- A ‘separator’ holds seed in place until after fire & rain
- swells and pulls seed out -the fruit= called a follicle -each “diamond” was a flower, only a small proportion develop into fruit follicle= fruit that opens up, splits, like a mouth
- often fruits open after fire
What is the common mechanism in Grevillea and other Proteaceae of making fruits fall to the ground?
they can helicopter a small distance away from the plant -separator= holds the seed in place until it rains= gets wet, swells up and pushes the seed out of the follicle -the seeds are protected from fire by tough outer capsule
What are fruits of Proteaceae like?
-usually dry and encased in a hard capsule -some are fleshy and edible= Edible nuts - 1. Macadamia rich in oils; only commercial crop based on a rainforest tree of Queensland 2. Fleshy sweet ‘drupes’- geebung Persoonia
What is the family of legumes defined by?
-defined by having these fruits= legumes, pods -open at maturity at the inner and outer edge -the pod= fruit -the pea= seed
How many Legume families are there in Australia?
- Peas (Fabaceae) 2. Wattles (Mimosaceae,Acacia) 3. Cassias (Caesalpiniaceae)
What is the fruit of legumes?
-pod -the pea (etc.) are the seeds
What are legumes used for?
-Food plants - peas and beans -Native species often toxic but used by Aborigines -Some a source of medicinal compounds or genetic traits (e.g. drought tolerance) for crop legumes e.g. Glycine traits for soy beans
How many representatives from the legume family Fabaceae are there in Australia?
• 1 100 spp. in Australia, 12 000 worldwide • trees • shrubs • herbs • creepers • climbers -vary in shape of plants, lot of them are shrubs -all types and sizes
What are the characteristics of Fabaceae (legume family)?
-Seeds have hard resistant coats - survive fire - Leaves often compound - 3 leaflets or more -Sclerophyll forms have simple leaves, reduced to spines or scales -Nitrogen fixing (often have nodules infested with bacteria= symbiosis= can fix atmospheric nitrogen so the plant can survive -important for agriculture, return nitrogen to the earth in a form that can be used by other plants as well (when decomposed)
What do the Fabaceae flowers look like?
- pea flower
- reproductive organs are in the keel petals
What are the pea flowers in the colour “egg and bacon” pollinated by?
-insect pollinated -Standard petal large, showy Yellow attracts bees Markings are nectar guides Keel and wing form a landing platform for the bee (Some peas, e.g. red flowered, are bird pollinated)
What is the flower variation in Nemcia? (Fabaceae)
-egg and bacon one -then bird pollinated type of the same genus= larger, red
How long have Acacias (Wattle family of legumes) been in Australia and how many species are there?
-since early Miocene -probably don’t go back to Gondwanan times -20 MY -it is the largest genus of woody flowering plants in Australia with 960 species
Where do Acacias occur? (Wattle family of Legumes)
-Occur in rainforests and wet eucalypt forest e.g. Acacia melanoxylon (blackwood) -Dominant in semi-arid and arid regions e.g. mulga lands -understory shrubs in the wetter regions, in very arid places they are dominant and bigger
Why are Acacias important?
-Green Acacia seeds roasted 18-25% protein content -Acacia gum - bush candy -Timber, e.g. blackwood A. melanoxylon -Important after fire - fix Nitrogen root nodules with bacteria: Rhizobium, return Nitrogen to the soil
What are the two foliage types of Acacias?
- bipinnate leaves
- phyllodes= more common in Australia, more sclerophyll-like
- often bipinnate as juvenile, phyllode as adult
What are the two types of flower arrangement in Acacias?
-either a flower spike(usually when phyllode) or globular flower head (when bipinnate leaves)
How does pollination work in Acacias?
-very small flowers, in clusters (heads or spikes). 1. Female phase style elongates, 2. Male phase pollen shed -reduce probability of indbreeding -as male and female phase= so more outcrossing -pollen grains are in multiples of four, together= polliates, aggregated -extra-floral nectaries on leaves or phyllodes; showy inflorescence of many flower clusters stamens are the most showy parts -some are bird pollinated but most by insects -glands on the branch, extra-floral nectaries= attract birds
Where can the nectar in Acacias be?
-on branches when bird pollinated, attracts them as lot of it
What can the extra-floral nectaries of Acacias also attract?
-ants • Ants not pollinators BUT can: • Keep plant relatively free of fungal spores • Ward off herbivorous insects
What are Acacia fruits and seeds like?
- Fruit a legume (pod) • seed coat hard - seed won’t take in water and germinate until this is cracked (e.g. by heat of fire) • often have an eliasome - ants take seeds underground
