1. Cycadophyta (Cycads):

* Ancient lineage, resembling palm trees

* Large, compound leaves

* Dioecious (separate male and female plants)

* Examples: Cycas, Zamia, Dioon

2. Ginkgophyta (Ginkgoes):

* Only one living species: *Ginkgo biloba*

* Fan-shaped leaves with distinctive veins

* Dioecious

* Resistant to pollution and disease

3. Coniferophyta (Conifers):

* Most diverse group, with over 600 species

* Woody, cone-bearing trees and shrubs

* Needle-like or scale-like leaves

* Examples: Pines, spruces, firs, cedars, redwoods

4. Gnetophyta (Gnetophytes):

* Smallest group, with only three genera

* Diverse in appearance, including trees, vines, and shrubs

* Some species have vessel elements in their wood, a characteristic more typical of angiosperms

* Examples: *Ephedra*, *Gnetum*, *Welwitschia*

These classes are further divided into orders, families, genera, and species. Each class has distinct characteristics that differentiate them from one another.

Here's a table summarizing the key features of each class:

| Class | Common Name | Key Features | Examples |

|---|---|---|---|

| Cycadophyta | Cycads | Large, compound leaves, dioecious, slow-growing | *Cycas revoluta*, *Zamia furfuracea* |

| Ginkgophyta | Ginkgoes | Fan-shaped leaves, dioecious, resistant to pollution | *Ginkgo biloba* |

| Coniferophyta | Conifers | Woody trees and shrubs, needle-like or scale-like leaves, cones | *Pinus strobus* (Eastern White Pine), *Abies balsamea* (Balsam Fir) |

| Gnetophyta | Gnetophytes | Diverse in appearance, some have vessel elements | *Ephedra distachya*, *Gnetum gnemon*, *Welwitschia mirabilis* |