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Seed Plants II: Angiosperms (Concepts (evolutionary changes involved in…
Seed Plants II: Angiosperms
Concepts
earliest fossils found date back 1.3 million years ago but no fossilized flowers have been found intact from that time :skull_and_crossbones:
first angiosperms were most likely small trees or shrubs well adapted to dry climates
evolution of gymnosperm to a flowering plant took long time and went through many iterations :star:
conversion of gymnospermous sporophylls into stamens and carpels resulting flowers
reproductive parts are more relictual
anigosperms and other clades are when evolved in their own right but angiosperms tend to have more adaptations
angiosperm carpels contain edges of sporophyll primordia that crowd each other and grow shut leaving a visual structure :red_flag:
closed carpel occurs when primordia closes almost completely shut and develops fruit that encloses embryos that develop into seeds :black_flag:
carpels in basal angiosperms are leaf-like resembling young leaves whose blades have not opened yet
ovules in gymnosperms are exposed on the megasporophyll surface, folded nature offers protection and a pollen tube :checkered_flag:
the flowering plant clade angiosperm contain the largest number of living members :check:
classified together as a single division named Magnoliophyta :black_flag:
common to refer to angiosperm as most advanced group of plants, peak of plant evolution with most derived features
group is named for having flowers and a positive interaction with animals which results in pollination and spread of seeds :check:
has also become more adapted to fight animals as well, rewarding pollinators and hurting predators, chemical responses :warning:
fertilization evolved so that a second sperm cell of the pollen tube fuses with polar nuclei of megagametophyte producing the endosperm nucleus in a process called double fertiliztion :star:
structural modifications are most easily seen but more fundamental transition was the acqusition of developmental plasticity :check:
conifers lack this plasticity
evolutionary changes involved in the conversion of a gymnospermous lines into a angiosperm did not occur instantly :<3:
ability to produce bisexual flowers
vessel elements evolved next
few plants are considered primitively vesselless which they lack vessels because their ancestors lacked them :check:
others arose after vessels had originated but then they lost them are called secondarily vesselless plants :red_flag:
double fertilization was first transformation
ability to have an annual habit and shurb-like beginning plant helps angiosperms develop the look and patterns we know today
other features derived are
pistil which is the fusion of the carpels into a single structure :check:
sympetally the fusion of petals into one structure
floral zygomorphy that flowers are bilaterally symmetrical not radially symmetrical :black_flag:
Classification of Flowering Plants
flowering plants began to follow two distinctive lines of evolution and all angiosperms are classified as :star:
monocots
usually have parallel veins because the leaves are elongate and strap shaped . Flowers have 3 petals, 3 sepals, 3 carpels :black_flag:
eudicots
more diverse, 2 cotyledons, reticulate venation, vascular bundles present in one ring of stem, can be woody :checkered_flag:
no single characteristic distinguishes a monocot from a eudicot. monocots only have one cotyledon on each embryo :check:
Basal angiosperms are early angiosperms that diverged into several clades. Are not newly discovered species :check:
Magnoliophyta is large group with many families, genera, and species. Rare for taxonomist to study entire group.
Monocots
Commelinoid Monocots
Arecales
contains the palms and consists of 3,500 species which are recognized by the solidarity of their trunks
leaves always occur near shoot apex, never distributed along the length of the stem. have simple leaves :check:
have scattered vascular bundles
Poales
found in abundance in open areas such as the plains in the US and Argentina and the savanna in Africa :checkered_flag:
are wind pollinated so sepals and petals are of little importance. the 3 carpels fuse together but in grasses they remain separate :!:
include foods such as wheat and corn and sugar cane. 50% of all calories consumed by people from from these related grass seeds :check:
similar to grasses are sedges and rushes which are the grasses found in marshes such as the Everglades :check:
contain grass families as well as other familiar groups such as cattails. 8,000 species :star:
cattails grow in ponds and marshy areas, have thick horizontal subterranean rhizomes and other axillary buds growing upward. is basically a single branch :red_flag:
bromeliaceae commonly know as spanish moss and ball moss are found from Florida to Texas and contain beautiful tropical epiphtyes, brightly colored inflorescences :check:
consist of 4 orders as they differ form others in unusual synapomorphies. Have unique epicuticular wax :surfer:
walls have ususual types of hemicelluloses and ultraviolet- fluorescent compounds :check:
pollen contains starch and does their endosperm.
Zingiberales
differ from other monocots as they tend to have large, showy flowers pollinated by insects, birds, etc.
flowers have derived features, adjacent sepals and often fused together forming a tube, true for petals as well. gynoecium consistis of 3 carpels that have almost fused completely. :check:
contain familiar house plants and are best known in the southern states :sunny:
largest family has approximately 1,000 species. Almost all are tropical and soft nonleathery herbs with broad leaves and petiole :star:
monocots are believed to have arisen form ealry angiosperms approximately 80 to 100 million years ago :check:
Perianth usually consists of three outer and three inner members that look very similar and are called tepals :red_flag:
theory about parallel venation of monocot leaves postulates that the ancestor had broad leaves and lived s aquatic plants :recycle:
leaves evolved to a reduced, simple type without a blade, more adaptive for submerged leaf :checkered_flag:
others developed on land made strap-shaped leaves and braodleafs evolved to be advantageous to more light
all monocots lack ordinary secondary growth and wood, ancestors were probably without vascular cambium or little activity :star:
early monocots diverged into a series of clades whose extant members are classified into approximately ten orders :star:
Liliales
genus
Smilax
contain tough fibrous vines with leaves that have petiole and broad lamina with reticulate venation. :red_flag:
one of the largest families, Liliaceae contains ornamental plants that they are thought of typical monocots :green_cross:
small clade with 11 families and 1,300 species. Presence of spots or lines on petals or ordinary nectaries formed at bases of tepals or stamens
Asparagales
form a septa by carpels fusing side by side starting at their bases. Due not fuse all the way up to the style, create open areas to secrete nectar called septal nectaries :bee:
very diverse groups with different adaptations, most plants are like onions or corms, other are like Agaves and yuccas
there are several morphologic and DNA synapomorphies that unite this group.
have diversified biochemically with different groups have distinctive chemical compounds :warning:
flowers are large, colorful and showy and numerous types of insect pollination have evolved :check:
Orchidaceane is the largest and most diverse family of Asparagales
produce hundreds or thousands of tiny seeds in each fruit. Seeds are dustlike and undeveloped at germination must form symbiosis with certain fungi :red_flag:
ornamental ones and epiphytic many are terrestrail and one is a subterranean parasite :check:
alismatales
mostly found in swamps and marshes, partly or entirely submerged, developed plesiomorphc features in response to external pressure :!:
have no transpirations thus mutations are reduction of stomata and ir chambers develop.
cantain many aquatic herbs and many aquarium plants
plants do not waste carbon and energy producing fibers for support as they are not needed :star:
Tend to thin and delicate due to simplification of tissues
most relictual members have flowers that are large and showy with 3 sepals and 3 petals but other can be highly modified :checkered_flag:
Dioscoreales
yams are starchy tubers produced by several species in this family and a major source of carbohydrates :zap:
have petiolate, braod leaves with reticulate venation and are easily mistaken for dicots
small order with only one family
Eudicots
Rosid Clade
DNA analysis has been the best to in discovering the relationships of such a diverse clade :star:
consist of several small orders and two large groups
the 2 large clades are :star:
fabids (eurosids I)
malvids (eurosids II)
together contain more than a 100 families and as a group are very diverse
one small group contains few members bt has a huge economic significance which are the grape families used to produce wine, juice, raisins, etc. :grapes:
rosid clade onsists of many families that are so diverse in respects to morphology that it is hard to see how the are related :no_entry:
named after the order Rosales, roses should not be considered typical, consist of 14 large orders and 50,000 species :black_flag:
5 orders contain 75% of the population :!!:
Myrtales (
Eucalyptus
) 9,000 species
Malpighiales (poinsettia) 1,600 species
Fabels (legumes) 19,000 species
Rosales (Roses) 6,300 species
Sapindales (maples) 5,800 species
rose family is important not only in an evolutionary sense but economically. :check:
Remaining eudicots are members of two very large diverse clades the rosids and asterids :check:
many have root nodules with symbiotic associations with nitrogen-fixing bacteria and can grow in poor soils. :star:
important for food, drugs, dyes, and woods
Bodies can vary from trees to shrubs vines, and herbaceous annuals :recycle:
Basal Eudicots
hamamelid families believed to be basal eudicots. are large wind pollinated trees with flowers in dangling infloecences containing many staminate flowers :black_flag:
Carophyllales
another unifying character is that endosperm develops only a little then fails to continue growing, nucellus cells proliferate and form nutritive tissue called perisperm :star:
3rd feature is the nature of sieve tube plastides where phloem plastids deposits fibrous protein located as a ring interior to plastid membrane :check:
other flowering plants have anthocyanin pigments in the flowers, Carophyllales prodce water soluble pigments called betalins :red_flag:
most members are herbaceous with either no wood very little wood or unusual anomalous wood :check:
include cacti, spinach, beets and iceplant.
originated in Gondwana but separated due to continental drift, moving them all over the world and to different continents :green_cross:
include carnivorous plants such as the Venus flytrap
poppy family is known for ornamental species as well as a species that is used for opium. Unusually herbs or shrubs with soft wood
Santalales
includes tree that's roots tap into surrounding plants and feeds off them and the common mistletoe
some members of mistletoe are holoparasitic and have no chlorophyll at all :!:
small order of highly modified plants, most of which are parasitic :star:
Ranunclaceae has flowers with little fusion, each flower has many stamens adn carpels that remain separate :<3:
Asterid Clade
Many chemical differences exist between this group and all others, lack specialized chemicals found in other clades :red_flag:
has no betalins, benzyl-isoquinoline alkaloids, ellagic acid or proanthocyanins :black_flag:
instead contain irioid compounds which occur only rarely outside the group :check:
many can produce very potent chemicals that can deter or kill animals, a produce of evolutionary defense :star:
astrids have the greatest number of species (60,000) but are grouped into 2 small orders
orders Lamiids (euasterids I)
campanulids (euasterids II)
3 distinctive features that determine asterid clade :recycle:
they always have just a few stamens, not more than the number of petal lobes
stamens alternate with petals
they have sympetalous flowers (their petals are fused together into a tube) :check:
asterids exploit very specialized pollinators that recognize complex floral patterns :star:
one family Asteraceae contains 1/3 of all species and is the largest family of eudicots :star:
other examples include milkweeds, potatoes, tomato, red peppers eggplants tobacco :hot_pepper:
originated around 60 million years ago just like the sister clade rosids :timer_clock:
many asterids are extremely important medicinally. :check:
the periwinkle can be used to extract vinblastine and vincristine which is a potent anti cancer drug :check:
heart disease can be treated by a plant from the snapdragon family
most derived large clade of eudicots os the asterid clade which contians plants such as the sunflower, periwinkle, and petunia :check:
order Lamiales are used for their decorative and floral characteristic :star:
flowers tend to be bilaterally symmetrical and of sizes and shapes that permit only certain pollinators to enter :bee:
they produce certian floral patterns, fragrances etc, to attract pollinators for efficient pollination :<3:
family Asteraceae contains 1,100 genera and 20,000 species distributed worldwide :!:
are easily recognizable and contain wide range of unique chemical defenses against herbivores :check:
the chemicals make composites extremely resistant to animals that eat plants or lay eggs in them. Can cause skin irritation in some cases causing dermatitis. :red_flag:
range from important food plants to ornamental to weeds.
family is considered younf (36 million years old) originating in the Oligocene Epoch of the Tertiary Period :<3:
constitute a much larger group than the monocots and are divided into numerous clades which have diversified into many families :star:
a distinctive feature is that their pollen grains have either 3 germination pores(tricolpate) or condition derived from this :red_flag:
flower parts are arranged in whorls and stamens usually have well defined filament and anther.
every type of organ, tissue, and metabolism has several or many variations and more difficult fo characterize than monocots :!:
Basal Angiosperms
Eudicots have 3 germination pores :check:
important feature is taht their pollen grains have only a single germination pore, they are uniaperturate :star:
basal angiosperms contain living descendants of several groups that originated while angiosperms were young :check:
they became reproductively isolated
three extant descendants
Amborellaceae, small trees form New Caledonia, wood contained tracheids but no vessels and little parenchyma
Nymphaeaceae, water lilies, soft bodies herbs with vascular bundles scattered like in monocots lack any wood :red_flag:
Austrobaileyales
changing Concepts about early Angiosperms
C.E. Bessey developed hypothesis of the ranalean flower in which a
Magnolia
flower was considered relictual :red_flag:
carpels are in a superior position, easy to find generalized ancestor
angiosperms are monophyletic :check:
double fertilization
flowers and plasticity did not evolve more than once
such flower is generalized as it has all parts and are arranged spirally. :check:
original identification of fossilized leaves contributed to the erroneous hypothesis that angiosperms originated in Jurassic Period :black_flag:
oldest wood seems to be from Aptian Epoch 125 million years ago in Japan, flowers fruit produced in lower Cretaceous Period
fossils consist only of abscised carpels or carpels attached to a receptacle
concepts about the nature of early angioperms have changed as our knowledge becomes more complete
wind pollinated trees became most relictual living flowering plants
this provided a convergent evolution to allow these trees to be flowering plants/ angiosperms :check:
