Gymnospores by

Let’s talk: GYMNOSPERMS

salihaemely2 — 2025-08-06 14:24:21 UTC

2. Gymnosperms were amongst the first to produce seeds! But why is this a cool development?

salihaemely2 — 2025-08-06 14:29:18 UTC

1. Can anyone tell me what classifies plants as gymnosperms? (and for 5+ bonus points lay out the taxonomy)

salihaemely2 — 2025-08-06 14:32:24 UTC

4. If you guessed “Seeds create an open niche” then you got it!

salihaemely2 — 2025-08-06 14:36:42 UTC

This means: these plants no longer depend on constant water, but are now able to move to more open, dry areas.

5. To answer the last comment: no, seeds will not sprout every time one is carried away from its home tree. Seeds have evolved to manage being dormant for days, years, or until the time is right to germinate. They are able to do this because seeds have a supply of stored food that allow less concern of finding nutrients.

salihaemely2 — 2025-08-06 14:44:29 UTC

6. Great catch! Yes, gymnosperms are heterosporous - this means: their reproductive strategy involves two distinct types of spores (MEGAspores and MICROspores)

salihaemely2 — 2025-08-06 14:58:06 UTC

Let’s see who can guess which category they each fall in…TO THE NEXT POST!

7. Who all said that female structure produce MEGAspores and male structures produce MICROspores? Because if you did…you would be…RIGHT!

salihaemely2 — 2025-08-06 15:00:34 UTC

CHEAT SHEET - female structures produces the egg, and male structures provide the pollen! Here’s how to distinguish the two: look at their cones, leaves, and habitat!

salihaemely2 — 2025-08-06 15:05:17 UTC

3. When did they appear?

salihaemely2 — 2025-08-06 15:09:58 UTC

They appeared around 305 million years ago. They used to be dominant, but unfortunately many of their ancestors have gone extinct…

8. MALES - Staminate cone

salihaemely2 — 2025-08-06 15:27:20 UTC

Outer structure: Made up of pods and each pod called a Sporophyll or “spore leaf”.

Internal structure: Sporophyll are arranged around a cone axis. Inside, there is microsporangium - a sack that contain a much of cells called microsporocytes (recall?) that produce the pollen

9. FEMALES - Ovulate cone (most pine cones)

salihaemely2 — 2025-08-06 15:28:09 UTC

Outer structure: the spring cone is small and fleshy - the cones open when they are ready to receive pollen, but tighten up when they’re not!

Internal structure: Each bract on a pine cone contain two ovules. The structure is protected by Integument, which has an opening called micropyle covered in a sticky sheet to collect pollen. Inside, there is the megasporangium that contains a single megasorocyte cell (egg)

10. When a mommy cone and a daddy cone love each other very much, what happens?

salihaemely2 — 2025-08-06 15:40:00 UTC

Well, they start their fertilization process!

Pollen grains are carried by wind or wing and find their way into the open scales of a female pine cone.

This pollen is then stuck on the sticky integument fluid at the micropyle (recall where this is-the opening).
More fluid is secreted that helps the pollen grains go into the ovule and then it dries and seals itself.
The male tube cells then extend themselves while the generative cells stays behind
And then, well…the rest is history (until the following year).

11. The following year later…

salihaemely2 — 2025-08-06 15:44:39 UTC

the pollen enters the neck cells - sperm is not fusing with the egg causing multiple zygotes (offspring) to (potentially) form.
When an offspring forms - it is as a 16 cell structure: the first four are the initials (eventually forming an embryo) and the other 4 are the suspensors (elongate to acquire nutrients
Plot twist? Only one survives.
The surviving one turns into a seed and the cycle repeats

12. A baby is born!

salihaemely2 — 2025-08-06 15:52:44 UTC

When the seed finds the earth (and when the timing is right) the seed will begin to root and grow.