Ch18

Vascular Cambrian produces wood


Secondary phloem (inner bark)


Secondary phloem outside, then secondary xylem

It has anticlinal growth. Anticlinal growth means


The epidermis also needs to grow: or cambium


Basically memorize the anatomy of a tree cookie. This WILL be on the final exam.


Pollen differentiation among gymnosperms


All ginkgo and cycads have pollen tubes that are haustorial (parasitic, feeding off the nucellus as it grows)

Cycads and Gingos have sperm that swim

CC=GG=SS (mnemonic)


Cycadophyta= Cycads

generally short, typically 1-5m

Not a close-relative to palms

Slowly growing

Little secondary growth (explains short stature)


Cycads have little secondary growth


Cones heat up

You don’t want to eat it (neurotoxins)

Circulate Vern at ion of pinnate leaves

Ancient lineage adapted to living in tropical and subtropical regions

Dioecious (separate male and female plants)

S


Cone: single axis with

Male column: microstrolbili-bear microsporophylls, with microsporangia

female: megastrobili, bears megasporangiamegasporophyll

Male cones are tall and skinny

Under the cone (microsporabilii is microsporangia)

Female cones are short and fat

Produces 2 ovules on the megasporophyll


Exception to the megastrobili: the genus Cycas

The megasporophylls are NOT organized into an ovule cone

Big green dots are


The loneliest cycad

Encephalitis woods, a male of its species

A female has never been found: a dioecious problem. Lived in botanical garden for 100 years. Never found another one, use cuttings to grow new ones


two major families of cycads

Cycadaeae

Pinnate leaves with a single mid-rib but no lateral veins on leaflets


Zamiaceae

Pinnate leaves have no mid-rib but dichotomously branched longitudinal veins


Stangeria genus (under Zamiaceae

Pinnate leaves with a midrib and lateral veins


Cycadaceae

Single mid rib


Zamiaceae

No mid rib but dichotmously branched longitudinal veins


Midrib and lateral veins

Stager is Genus (under Zamiaceae)


Dichotomous key


  1. No mid rib: Zamiaceae

Midrib: see 2

  1. No lateral veins: cydeacea

lateral veins: stangeria genus


On the megastrobili

Megasporophyll + 2ovules

Each ovule develops into one megastore

The megastore develops into the me (didn’t finish


From insid to outside

Magagametophyte

NucellusIntegument

Microphyle


From inside to outside: microstrobilus



Generative cell

Prothalial cell


280 mya lives along the dinosaurs (230 mya)

However, indigenous communities have developed ways to detoxify these cycads seeds

Gen