Lecture 7 Fabaceae 1 PDF

Legumes  Family Fabaceae (1) General Background/ Distribution (2) Characteristics (3) Three families within a family? wMimosaceae (Wattles) wCaesalpiniaceae (Cassias/Sennas) wPapilionaceae (Peas)  OR Three subfamilies of Fabaceae wMimosoid...

Legumes  Family Fabaceae (1) General Background/ Distribution (2) Characteristics (3) Three families within a family? wMimosaceae (Wattles) wCaesalpiniaceae (Cassias/Sennas) wPapilionaceae (Peas)  OR Three subfamilies of Fabaceae wMimosoideae (Wattles) wCaesalpinioideae (Cassias) wPapilionoideae (Peas)  General Background & Distribution Worldwide: Third largest flowering plant group (18,000 species grouped into 650 genera). Greatest diversity is in tropical and subtropical areas (absent from Antarctica and the Arctic). Largest group in both Australia with 1885 species and in WA with over 1400 species. Many of the world’s important food, fodder and timber species (second to the grasses). Common name: Legumes  WA FAMILIES http://florabase.calm.wa.gov.au/statistics/WACensus_2007-06-01_table2.pdf  WESTERN AUSTRALIAN LEGUMES Monophyletic- now all considered one family -Fabaceae Number of (Genera) species Caesalpiniaceae ( 11) 52 Total Fabaceae ( 114) 1465 http://florabase.calm.wa.gov.au/statistics/WACensus_2007-06-01_table2.pdf  Family Fabaceae (1) General Background/ Distribution (2) Characteristics (3) Three families within a family? wMimosaceae (Wattles) wCaesalpiniaceae (Cassias) wPapilionaceae (Peas)  General Characteristics (1) Fruit = legume (pod) formed from a single superior carpel and dehiscent into two valves. When the legume is ripe it dries and splits along the line of dehiscence allowing the seeds to be released. Taken from:Picture Gallery for Melbourne, VICTORIA - Royal Botanic Gardens Exploding pods  Jiri Lochman The seeds are high in protein and are often sort out by native animals. Special relationship with ants The seeds often have special food bodies (called elaiosomes). Ants collect seeds and carry them to their nests to eat the food body. The seeds remain intact. These seeds have a higher chance of surviving because they are less likely to be attacked by seed predators and because they are placed in sheltered locations near the ants’ nutrient-rich refuse piles. elaiosomes http://commons.wikimedia.org/wiki/Image:Aclo_001_lhp.jpg http://www.bbc.co.uk/programmes/p00lxvrk  General Characteristics (2) Most fix Nitrogen due to association with bacteria (Rhizobium & Bradyrhizobium) in root nodules. Nitrogen is required for protein production. This is the reason why plants from this family are high in nitrogen and extremely useful as a source of plant protein.  General Characteristics (3) Habit: trees, shrubs, scrambling subshrubs, vines or herbs. Habitat: varies from deserts through to temperate forest to tropical rainforest and aquatic habitats. Three subfamilies: (1) Mimosoideae (wattles) (2) Caesalpinioideae (cassias) (3) Papilionoideae (peas)  Family Fabaceae (1) General Background/ Distribution (2) Characteristics (3) Three families within a family? wMimosaceae (wattles) wCaesalpiniaceae (cassias) wPapilionaceae (peas) These are actually subfamilies but in your books used in the lab they are separated into three families.  (1) Mimosaceae (wattles) Cosmopolitan family with about 60 genera. In Australia most common genus = Acacia: (widespread with over 1000 species). About 50% of Acacia species are from WA. WA also has one member of the genus Paraserianthus (mostly a tropical genus). Habit varies from small shrubs to large trees  (1) Mimosaceae (wattles) Acacias are often well adapted to arid conditions and are found in habitats that are too severe for even the most hardy Eucalypt. As a legume this genus is an important contributor to soil nutrition and is an early coloniser of disturbed sites. Acacia aneura (Mulga) distribution  The Wattle War -Listen ABC RN https://www.abc.net.au/radionational/programs/sciencefriction/acacia-name-africa-australia-wattle-war-botany-taxonomy/13372220 Australia’s emblem Australia’s national flower is the golden wattle (Acacia pycnantha). Australia’s national colours of green and gold were inspired by the colours of the wattle. Various shades of green and gold have represented Australia internationally since 1899. Wattle has been a culturally important plant for Aboriginal and Torres Strait Islander peoples for millennia. The first use of wattle as a symbol of Australia dates back to 1838 in Hobart, Lutruwita / Tasmania. Wattle Day on the first day of Spring (Sept 1) has been a national day of celebration in Australia since the early 1900s. The coat of arms of Australia features a spray of wattle. All of Australia’s ”next generation” banknotes feature representations of wattles (Acacia). After the Gallipoli campaign, Australian soldiers planted wattle as a symbol of remembrance.  Acacia Controversy DNA shows that the 1,300 species called Acacia are not monophyletic. Has led to Acacia being broken into five genera Much-debated and controversial re-typification of the genus with an Australian species (not the original African type species) due to iconic nature and large numbers of species in Australia (over 1000). This is an exception to traditional rules of priority that required ratification by the International Botanical Congress in Vienna in 2005. When the genus is divided, the traditional acacias of Africa are now treated in the genera Vachellia and Senegalia, American species are placed in Acaciella and Mariosousa, and Australian species in the genus Acacia Some taxonomists refuse to recognise this re-naming -The wattle war- listen ABC RN https://www.abc.net.au/radionational/programs/sciencefriction/acacia-name-africa-australia-wattle-war-botany-taxonomy/13372220 Distribution of original Acacia before separation into 5 genera  What’s a Type Species? A type species is the species that contains the original type specimen(s). Fundamental rule of nomenclature is that the first person to scientifically describe a species can give it a name and lodge it as the ‘type’ in a Herbarium. The ‘type’ specimen for the genus is based on the first species described from that genus. for Acacia it was Acacia nilotica – described by Linnaeus in 1753- it is native to Africa, Middle East and India- not Australian. DNA evidence shows Australian species are different at the genera level So based on this rule, Australian species should not be Acacia- they were not the first Acacia described. Re-typification in 2005 of this genus has now placed Acacia penninervis as the type specimen. It is the first described Australian species as an ‘Acacia’ even though DNA evidence now shows it to be different to the original Type for Acacia.  Want to read more? ‘It is an extraordinary tale of botanical intrigue... a team of Australian botanists pulled off the world’s greatest branding coup... with ferocious public support, massive documentation, and a superb public relations machinery.’…‘the South Africans underestimated the Australians (again!)’ (Montgomery 2006). O’Neill (2007), an Australian botanist, hailed the Vienna decision with relief for having escaped the ugly genus name Racosperma: ‘Had the proposal failed, Australia’s national floral emblem, the golden wattle, might now be Racospermum pycnantha’. The unstated assumption for the supporters of retypification was that by celebrating the wattle as a national symbol, Australia had gained the right to retain the euphonic name Acacia for its species. See link on BIO257 site or listen to ABC RN https://www.abc.net.au/radionational/programs/sciencefriction/acacia-name-africa-australia-wattle- war-botany-taxonomy/13372220  Floral Morphology of Acacias Acacia flowers are typically arranged in heads or spikes of many small flowers. The prominent part of the flower is the stamens that are exserted well beyond the perianth. Single flower  Floral Morphology of Acacias Flowers are actinomorphic (regular) and bisexual. Two whorls of inconspicuous petals and sepals which are valvate (ie. they meet at edges, not overlapping). The carpel as in all legumes consists of a single superior carpel containing few to many ovules. Page 30 in your manual Floral Morphology of Acacias  Vegetative Morphology of Acacias Woody trees and shrubs Leaves are bipinnate However many Australian species have their leaves reduced or lost and are replaced by phyllodes = flattened petioles that function as leaves. Phyllodes are flattened in the direction of the axis (true leaves are generally flattened at 90o to the axis).  Vegetative Morphology of Acacias For species with Phyllodes the first leaves are always compound true leaves but with development the leaf stalk flattens and leaflets become reduced and then absent. Phyllodes range from broad and typically leafy to very narrow and spinelike. From true leaves to phyllodes Photo: P. Makar Vegetative Morphology of Acacias bipinnate rigid articulating (decurrent with stem) = one leaf (compound)  Aboriginal uses of Acacias Seeds, seed pods and roots were eaten; the sticky sap was chewed or used to make a sweet drink, and the roots of some species are hosts to such delicacies as witchetty grubs and honey ants. The wood was used in the manufacture of spears, boomerangs and handles for stone tools and strips of bark were used in making fishing nets and bags. Current uses of Acacias Acacia bark is an important source of tannins for tanning leather. A number of eastern species provide valuable timber eg. Blackwood. Important in agriculture for shelter belts and stock fodder. Widely planted as ornamentals. For revegetation (nitrogen fixing) Current uses of Acacias- In cooking Wattle Seed Tiramisu (Contains 30g of toasted wattle seeds)  Acacia- iconic Australian flora The Golden Wattle (Acacia pycnantha) –National emblem The Golden Wattle flag- Australian sport colours Examples of Acacias Examples of Acacias (i) Mimosaceae (key to Genera) B & G part 2 (i) Mimosaceae (Acacia) continued  (2) Caesalpiniaceae (cassias) The Caesalpinaceae found mostly in the tropics and sub-tropics (approx 150 genera with 2200 species). In Australia there are 19 genera with 85 species. In WA there are 11 genera with 52 species, many occur in the far north and the more arid inland. The largest, most widespread of the WA genera is Senna. One genus occurs in the Perth region- Labichea and Petalostylis is nearby.  Floral Morphology of Caesalpiniaceae There are few features that are unique to the Caesalpiniaceae (basically defined by lacking the features that are unique to the Mimosaceae & Fabaceae).  Floral Morphology of Caesalpiniaceae The flowers are zygomorphic (although may be considered nearly regular in keys) and bisexual. Sepals and petals free Petals overlap the uppermost inside the rest (similar to the Fabaceae). Stamens: 7-10(Senna), 2 (Labichea) or 3 (Petalostylis) with 2 staminodes (undeveloped, sterile stamens). Floral Morphology of Caesalpiniaceae Page 30 in your manual  Vegetative Morphology of Caesalpiniaceae Leaves are pinnate or bipinnate, rarely simple or bilobed and occasionally reduced to phyllodes. Occurs as woody trees or shrubs.  Compound leaf terms: Pinnae versus pinnule Pinnate leaf Bipinnate leaf Leaf Petiole Stem or branch of plant  Uses of Caesalpiniaceae Tamarind Pod There are a few economically important species in this family but most of these are not endemic to Australia. Senna pods provide a powerful laxative, Mesocarp of tamarind (Tamarindus) pods used in e.g. chutneys, jam, drinks, sorbet, icecream, Worcestershire & HP sauce. Ceratonia pods give carob. Many ornamental exotic species are cultivated e.g. Gleditsia (Honey locust), Cercis (Judas tree) and Bauhinia (Orchid tree). (ii) Caesalpiniaceae (key to genera) B & G pt 2  Examples of Caesalpiniaceae Labichea sp (only two stamens) Examples of Caesalpiniaceae Senna sp (note 7-10 stamens but not always equal size)  Examples of Caesalpiniaceae Petalostylis sp 3 stamens, 2 staminodes, petal like style- works like a landing platform for iinsects