Botany Unit Notes Part II

Seed Producing Plants Plants require water to photosynthesize sugars and make food Many plants even need water for reproduction! The evolution of seed plants did away with the need for water in reproduction This was one reason leading to the success of seed plants on Earth

Seed Producing Plants Seed plants form male and female gametes Sperm are the male gametes and they are in the form of pollen The female gamete is an egg Pollination is when a pollen grain fuses with the egg cell of the female plant/organ

Advantages for Seeds Seeds nourish and protect plant embryos Under the right conditions a seed will germinate (next slide) Seeds allow plants to be dispersed other places Seeds can pass through the digestive system of most animals without being damaged

Seed Germination

Types of Seed Plants There are Two types of Seed Plants: Gymnosperms are seed plants that do not produce fruits Most have cones as reproductive organs like pine trees and cycads Gymnosperm means “naked seed” Angiosperms are the flowering plants that do produce fruits and have flowers as reproductive organs “enclosed seed”

Gymnosperms Gymnosperms make up 3 distinct groups: Gnetophytes – phylum Gnetophyta makes up about 70 species today and are considered “living fossils” Cycads – phylum Cycadophyta are palm-like plants that reproduce using large cones and appeared around 225 mya! Conifers – phylum Coniferophyta are the traditional “pine trees” making up the majority of Gymnosperms with 500 species

Conifer Life Cycle

Angiosperms Angiosperms are also called flowering plants They have flowers as their reproductive organs Angiosperms produce many different kinds of fruits Fruits are considered the wall of tissue surrounding the seed Fruits come in many forms like an apple or a dandelion

Angiosperms Angiosperms owe their success to their ability to attract pollinators and seed dispersers Animals that eat the fruits can pass the seed through their digestive tracts and deposit the seed far away from the original plant!

The Flower Flowers have male and female organs Ovule = egg Pollen = sperm Pollen “stick” to the top of the stigma and travel down the style to the ovary (pollination)

Angiosperm Life Cycle

Angiosperm Diversity Angiosperms are the most diverse plant group on the planet with over 230,000 species! We can categorize Angiosperms based on three traits: Monocots & Dicots (aka. Eudicots) Woody & Herbaceous Annuals, Biennials, and Perennials

Monocot vs. Dicot

Monocot vs. Dicot Monocots have fibrous roots while Dicots have taproots

Woody vs. Herbaceous A plant’s stem is an identifying characteristic It can be herbaceous when it is soft and easily cut with sheers It can also be woody and be rough to the touch like the bark of a tree

Plant Lifespan Plants can live anywhere from one year to several years Annuals – are plants that mature from seeds, produce flowers & fruit, and die all in one year Biennials – are plants that take two years to complete their life cycle storing some of their nutrients in underground rhizomes at the end of the first year Perennials – are any flowering plants that live for more than two years