BIOL 317: Plant Identification and Classification Summer 2015 - Notes

Week 5 – Tuesday  Malpighiales  morphologically heterogeneous clade  other important families include Hypericaceae (Saint-John's-wort), Passifloraceae (passionflower), Violaceae (violet), and Linaceae (flax)

 Euphorbiaceae (spurge family)  218 genera, 6745 spp.  distributed widely, but especially diverse in tropics  herbaceous or woody  leaves - simple or compound; alternate or opposite; stipulate  flowers • unisexual, plants monoecious or dioecious • usually actinomorphic • sepals none or 2-6 • petals none or 1-6 • stamens 1-many • pistil compound (3 carpels); ovary superior . 1 ovule/carpel . 3 styles, each usually divided • fruit: schizocarp (dry fruit that splits into usually one-seeded sections called mericarps)  genus Euphorbia - largest genus in family and among largest genera of angiosperms, ~1800 spp. • milky latex, often poisonous and caustic - defense against herbivores • inflorescence: cyathium . example of pseudanthium - inflorescence that as a unit resembles a typical single flower . whorl of 4-5 bracts forming cup-like involucre with usually 5 nectar glands . reduced staminate flowers consist only of single stamen . reduced pistillate flower consist only of single pistil . cyathium sometimes subtended by additional showy bracts that attract animal pollinators • many succulents, including cactus-like forms, especially in arid habitats of Africa  includes PNW weeds (Euphorbia maculata – milk spurge, etc.), food crop (Manihot esculenta – cassava), material crop (Hevea brasiliensis – rubber), and ornamentals (Codiaeum variegatum – croton, Euphorbia pulcherrima – poinsettia, Euphorbia spp. – spurge, etc.)

 Rosales  other important families include Rhamnaceae (buckthorn), Cannabaceae (hemp), Urticaceae (nettle), Ulmaceae (elm), and Moraceae (fig)

 Rosaceae (rose family)  90 genera, 2520 spp.  distributed widely, but especially diverse in northern temperate zone  herbaceous or woody  leaves - simple or compound; alternate; usually stipulate; margins often serrate  flowers • actinomorphic • hypanthium (usually cup-shaped structure formed by fusion of base of sepals, petals, and stamens) • sepals 5 • petals 5 • stamens many • pistil variable . pistils simple, 5; ovary superior - subfamily Spiraeoideae  fruit: aggregate of follicles . pistils simple, many; ovary superior - subfamily Rosoideae  fruit: aggregate of achenes or drupelets . pistil simple, 1; ovary superior - subfamily Prunoideae  fruit: drupe . pistil compound (5 carpels); ovary inferior - subfamily Pomoideae  fruit: pome (fleshy fruit in which much of the tissue is derived from the hypanthium rather than the ovary wall)  traditional subfamilies have been revised in more recent classifications since only the Prunoideae and Pomoideae are monophyletic. Spiraeoideae was paraphyletic, and Rosoideae was polyphyletic. New subfamilies correlate better with chromosome number and other traits besides fruit type.  includes PNW wildflowers (Rosa spp. – roses, Rubus spectabilis – salmonberry, Amelanchier spp. – serviceberries, Prunus spp. – cherries, Potentilla spp. – cinquefoils, etc.), food crops (Rubus spp. – raspberries, blackberries; Prunus spp. – cherry, peach, plum, almond; Fragaria spp. - strawberry, Malus domestica – apple, Pyrus communis – pear, etc.), and ornamentals (Rosa spp., Prunus spp. – flowering cherry, etc.)

 Fabales

 Fabaceae/Leguminosae (bean family)  745 genera, 19560 spp. - third largest family of angiosperms  distributed widely  herbaceous (more common in temperate zone) or woody (more common in tropics)  leaves - simple or compound (many pinnately compound); alternate; stipulate  flowers • sepals 5, usually fused • corolla and androecium variable among traditional subfamilies Faboideae/Papilionoideae Caesalpinioideae Mimosoideae Symmetry bilateral radial or bilateral radial Corolla petals 5, mostly free petals 5, free petals 5, fused, 1 - banner uppermost petal on not showy 2 - wings inside 2 - keel (fused at tip) uppermost petal on outside Androecium stamens 10 stamens 5 or 10, stamens many, filaments all fused, or free filaments fused, 9 fused, 1 free (diadelphous) showy

Petal arrangement:

• pistil simple, 1; ovary superior • fruit: legume (dry fruit with 2 sutures, or lines of dehiscence; sometimes also called a pod)  traditional subfamilies have been revised in more recent classifications since only the Faboideae and Mimosoideae are monophyletic. Caesalpinioideae was paraphyletic, and the other two subfamilies were derived from Caesalpinioid ancestors.  plants often form symbiotic relationship with nitrogen-fixing bacteria (Rhizobium) in root nodules  includes PNW wildflowers (Lupinus spp. – lupines, Astragalus spp. – milk-vetches, etc.), PNW weeds (Cytisus scoparius - Scotch broom, Vicia spp. - vetch, etc.), food crops (Glycine max – soybean, Phaseolus vulgaris – green bean, Pisum sativum – garden pea, Arachis hypogaea – peanut, Lens culinaris – lentil, Vigna unguiculata – black-eyed pea, etc.), and ornamentals (Wisteria spp., Laburnum anagyroides – golden chain tree, Albizia julibrissin – Persian silk tree, Robinia spp. – locust, etc.) Plant reproduction and breeding systems  Differences between plant and animal lifestyle and development Plants Animals sessile - must rely on intermediary for usually mobile transfer of male gametes usually bisexual usually unisexual body plan modular body plan fixed sexual expression can be dynamic over sexual expression fixed space and time  Asexual reproduction - produces genetically identical offspring (clones)  Vegetative reproduction - does not involve typically sexual organs • specialized structures: . rhizome - underground horizontally growing stem . stolon - aboveground horizontally growing stem . stems rooting/cuttings - detached stems can grow adventitious roots . layering - long, drooping branches can grow adventitious roots where they contact the ground . bulblets - daughter bulbs grows off of and detach from mother bulb . bulbils - daughter plantlets grow off of mother plant; can develop on leaves, in place of flowers, etc. • especially common in Salicaceae, Crassulaceae, among other groups  Agamospermy/apomixis • production of embryo in seed via mitosis of diploid cell in parent • common in Taraxacum officinale - dandelion  Sexual reproduction - offspring is result of combination of genes from maternal and paternal parents  pollination (transfer of pollen grain from anther to stigma) precedes fertilization (fusion of sperm and egg)  Selfing/autogamy - pollination and fertilization of gametes from same individual • cleistogamy - adaptation to promote selfing within individual flowers . non-showy, closed flowers  Outcrossing - pollination and fertilization of gametes from different individuals - Adaptations to promote outcrossing: • self-incompatibility . biochemical reaction prevents pollen grain from germinating and growing on stigma of same individual (and other individuals with same alleles as pollen grain at S-locus) • dichogamy - temporal separation of sexes . protandry - anthers mature before stigma is receptive . protogyny - stigma is receptive before anthers mature • herkogamy - spatial separation of sexes . heterostyly - different individuals have flowers of different morphs: stigma above anthers, or anthers above stigma . unisexual flowers  plants can be monoecious or dioecious