BIOA02H3 Lecture Notes - Sanguinaria, Meristem, Primordium
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January 7th~Feb1 2013
Midterm date: Monday Febuary 4th 2013. 5-7pm
Module 2: Begins on Tuesday Feb 5th.
Total: 12 lectures
1-2: Tree of life-plants
3-4 Plant cells and plant tissues
5-6. From seed to tree
7-8. From tree to seed
9. Transport in plants
10. Plant nutrition and soils
11. Plant defense
12. Plant life on the edge.
Lecture 7 notes (From tree to seed);aka sex in plants
1) plant sex organs
Generalized flower structure: 4=stamen,carpel,sepal,petal
Male: anther + filament=stamen
Female: stigma + style+ ovary = carpel
Sepal(sepal covers petal)
Protects inner flower organs before bud opens
Can be used to form tubes
Typically colorful to attract pollinators
Can be fused to form tube.
E.g violet, walsteinia, bellflower
Anther: pollen produces. Has 4 pollen sacs
Stigma: sticky landing platform for pollen (e.g. kiwi, poppy, tulip)
Style: connects stigma with ovary (Azalea, primrose, lily,)
Ovary contains one to multiple ovules. Ovules contain egg cell.
o Syncarpous ovary: many ovules (e.g cucumbers)
Shoot apical meristem-generative to reproductive organs
Turns from leaf primordium into flower primordium
E.g arabidopsis thaliana.
Is the evolution of flower originated from modified leaves?
Different genes of rings: carpel>stamen>petal>petal
Shoot apical meristem>flower primordium?
ABC model of flower development
A,B,C genes specify the four different flower organ types
Each of these genes is active in two adjacent rings of cells
A+B = petals organ
2) plant sex is not as boring as animal sex
some plants can have missing sepals or petals
E.g sarcandra: no sepal, no petal
Chickweed: no petal
Golden saxifrage: no sepal
Meadow rue: no petal, no female organ.
6% of angiosperms are unisexual=dioecious flowers. (one male plant, and one
female plant only just as how there is only one male, and one female)
E.g asparagus, hemp
17% are monoecious=both genders (one male flower and female flower organ in the
E.g hazelnut, corn
75% complete flowers are hermaphroditism=perfect flower.= male & female on the
same flower in the same plant
e.g trillium, rubus odoratus, blue cohosh, evening primose.