L15 Plants pt 2 Flashcards
What are the two ways we can classify land plants regarding their diversity?
nonvascular and vascular plants
non-vascular plants (aka _________) are represented by 3 groups:
- byrophytes
- mosses, liverworts, and hornworts
describe nonvascular plants
- small, simple, tough, and the 1st plant lineage to diverge after plants moved onto land
- lack vascular tissue, can dehydrate faster
why are nonvascular plants small
constraints on fertilization
- sperm from male gametophyte requires water to move to female gametophyte
- sperm can only travel short distances
describe the structure of a nonvascular plant
simple w/ flattened photoosynthetic structures (thallus)
- only a few cells thick
- lack internal air spaces
- no water conducting system
what type of -phyte dominates the life cycle of nonvascular plants, and why
haploid gametophyte
- larger than sporophyte
- independent and supports nonphotosynthetic sporophyte
describe the ecological importance of nonvascular plants
- small part of plant community
- peat bogs are useful
- makes acidic and wet conditions, producing phenols and slowing decomposition
- can store large amounts of organic carbon
- vulnerable to climate change
what -phyte dominates in vascular plant life cycle and why
diploid sporophyte
- larger and independent
- evolved vascular tissue
- less dependent on water for production
what can we divide vascular plants into
seedless and seed plants
what groups can we represent seedless plants with
lycophytes and ferns/horsetails (pterophytes)
pterophytes are a ______-phyletic group
monophyletic
describe the structure of a seedless (fern/horsetail) plant - consider leaves, stem, and growth size
- fronds are distinctive b/c they are divided into pinnae
- stems grow underground (invasive)
- vascular tissue allows plants to grow larger (b/c size is limited by lack of secondary vascular tissue)
Explain seedless plant history
grew to considerable size during wet period (~400mya)
- disappeared when climate changed and swamps dried up
- decomposed slowly (buried making coal deposits)
what is the importance of seed plants
- dominant producers on land
- don’t require external water source for fertilization
- seeds have embryo and nutrients (endosperm) with protective coat
- pollen: use wind or animals for dispersal of male gametes
what 2 phyla are represented by seed plants
gymnosperms and angiosperms
describe gymnosperms
- have “naked” seeds unenclosed by ovaries
- divided into 4 distinct groups
- better adapted to drier conditions
- conifers dominate in northern latitudes
describe cycads
- large cones and palm-like leaves
- able to live in nutrient-poor conditions
- most are tropical, but relatively few species exist today b/c on endangered species lists
- have insect pollination/animal dispersal
describe ginkgos
- popular ornamental tree with health benefits
- high tolerance to air pollution (therefore used in cities)
- only ginkgo biloba are alive
describe conifers
- most are evergreens (carry out photosynthesis all year)
- tolerate cold, dry conditions therefore outcompete angiosperms
key features of gymnosperm life cycle
- dominance of sporophyte generation
- seed development from fertilized ovules
- transfer of sperm to ovules by pollen (wind transport)
describe gnetophytes
- made of 3 genera
- some are tropical, some are desert
- have multicellular xylem vessels and double fertilization (same as angiosperms)
describe angiosperms
- flowering
- have protected seeds enclosed by ovaries and consist of 6 groups
- better suited to life on land
- diversity is still a mystery but it’s likely because of slower rates of species loss
what is the most widespread, diverse group of plants
angiosperms
how did earliest angiosperms evolve
- dominating gymnosperm forests
- insect pollinators
what are the rarer groups evolved of angiosperms
amborella, water lilies, star anise and relatives
describe magniliids
type of angiosperm
- include magnolia, laurels, black pepper, avocados
- common in early angiosperm evolution in tropical areas
describe monocots
~25% of angiosperms
- grass and grass-like flowering plants
- numerous food crops (rice, wheat, corn, sugar cane, bananas, ginger pineapple) and other economically important plants (bamboo, orchids, lilies, daffodils, tulips)
describe eudicots
includes ~75% of angiosperms
- 2 seed leaves upon germination
- numerous economically important plants (food, forests, gardening, health resources) and other plants (carnivorous, parasitic, epiphytes)
what are the differences between monocots and eudicots
- cotyledons (1 vs 2)
- vein pattern (parallel vs. netlike)
- vasc. tissue arrangement (scattered vs ring)
- root system (fibrous vs one main taproot)
- pollen grain openings (1 vs 3)
- floral organ multiples (3 vs. 5)
what does the evolution of plants show
adaptations that are more suitable to life on land
what are the phylogenetic relationships that account for plant diversity
- vascular vs. non vascular
- seed vs seedless
- naked vs protected seeds
