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To put this title into context, there are actually two basic kinds of angiosperms on Earth, showing here:

enter image description here

These differences in characteristics serve their own adaptations to survive and thrive.

Now let's say there is a THIRD type of angiosperm, one whose embryo numbers, leaf veinage, vascular bundle arrangements, roots and floral part multiples are not the same as the other two. Realistically, as far as adaptations to cosmopolitan varieties of environments and climates go, what would the embryos, veins, vascular bundles, roots and flowers of the third type look like?

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  • $\begingroup$ Your classification is a little out of date, dicots are actually paraphyletic, with quite a variety of internal structure. Here are few plants you can check out. en.wikipedia.org/wiki/Basal_angiosperms $\endgroup$ – John Mar 3 at 18:34
  • $\begingroup$ "A third type of angiosperm": there are more than three (main) types of angiosperms: Magnoliidae, Chloranthales, monocots (= Lilianae), Ceratophyllales, and Eudicotidae. Plus some odds and ends classified as basal angiosperms, of which the best known are the Nymphaeales. $\endgroup$ – AlexP Mar 3 at 20:02
  • $\begingroup$ I think you need to clarify the question. As AlexP said there are angiosperms that are neither monocot or dicot but they do not form a distinct third group. So the basic ideas of "two basic kinds" and "third kind" are kind of unclear. You seem to have some kind of concept you are looking for but just simplified biology too much for it to get across? $\endgroup$ – Ville Niemi Mar 3 at 23:53
  • $\begingroup$ @VilleNiemi Those "others" weren't major enough to count. $\endgroup$ – JohnWDailey Mar 4 at 0:57
  • $\begingroup$ That is exactly the kind of clarification that I wanted. What would make it major enough to count? And how different would those various details need to be? There is a limited amount of ways to organize these things. And different for the sake of being different is not really relevant to being the third kind, or is it? $\endgroup$ – Ville Niemi Mar 4 at 1:28
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How About:

  • Three cotyledons.
  • A single vein down the main of the leaf with orthogonal feeder veins. giving the leaf a heavy central cylinder that the leaf essentially flops on either side of.
  • Vascular Bundles usual organsied as a honeycomb, or latice like structure.
  • Several Tap roots present. Average three though as high as five or six. For the three case the roots are angled off the vertical be roughly 30 degrees.
  • Flower parts usually mirrored, preferring two, four, and eight part arrangements.

This would give you a distinct seed type, a reasonably functional vein structure, a rather sturdy tree probably good at resisting heavy weather due to the root spread, and an interesting flower form.

The only issue I can see are the leaves. This configuration would tend toward full leaf failure in the face of damage. Perhaps the leaves are generally more leathery? This would make the leaves more expensive biologically, but the theory would be that the leaf would resist damage, and be in use longer - similar to cacti and succulent leaves.

Is that what you are looking for?

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  • $\begingroup$ You are on track. $\endgroup$ – JohnWDailey Mar 4 at 11:59
  • $\begingroup$ I've been thinking--why not lattice the veins, too? That way, it wouldn't be so biologically expensive. $\endgroup$ – JohnWDailey Mar 6 at 0:41
  • $\begingroup$ There is no technical reason why not, It would still be a form of over engineering from a biological perspective. Not that this is a problem, the plant is fairly over engineered in its roots system, so being sturdy in other ways isn't a stand out. Lattice in the leaves would tend to degenerate towards the net-like structure leaf. Its has to do with flow, river systems and cardiovascular systems follow the rule too. The horizontal veins are still more tenable, because its a step difference from the other leaf patterns. Alternately it could be a throw back to conifer like needle leaves. $\endgroup$ – Kain0_0 Mar 6 at 4:13
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I asked my brother-in-law, who knows a lot about plants, and he wrote:

Monocots and dicots both have only a single embryo per seed. The writer probably got confused by the double fertilization process of zygote and endosperm that occurs in both monocots and dicots.

There are a number of extinct and extant non-angiosperm plants that could easily be re-imagine as a "tricot". Among extant plants, Gnetum and Welwitschia are lesser known gymnosperms with unusual growth habits. Among extinct plants, some that don't have any present day equivalents include the Pteridosperms, Cycadeoidea, Cordaites, Glossopteris, Lepidodendron, Archaeopteris, Chaloneria, and Sigillaria. The characteristics of any of these could be "mixed and matched" into a "tricot".

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  • $\begingroup$ The only problem with those analogues is that none of them have flowers. $\endgroup$ – JohnWDailey Mar 2 at 19:23
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    $\begingroup$ The extant cycads come pretty close to nonangiosperms with flowers. They have an organ which attracts beetles and weevils to serve as pollinators. That is one of the primary functions of a flower. Cycadeoidea might have been similar. $\endgroup$ – Willk Mar 2 at 21:39
  • $\begingroup$ @Willk But where are the petals? That's where I'm going. $\endgroup$ – JohnWDailey Mar 2 at 23:21
  • $\begingroup$ @JohnWDailey - you can look at the male and female flower analogs of the sago cycad here aggie-horticulture.tamu.edu/galveston/sago%20palm.htm. I think the evolution of flower analog structures has a lot to do with what mobile organisms are available to do the pollination. $\endgroup$ – Willk Mar 3 at 16:42
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    $\begingroup$ @JohnWDailey Ok, so imagine those analogues, but with flowers. You're asking for a hypothetical non-existent plant family, but you seem annoyed that it doesn't exist on earth? $\endgroup$ – ckersch Mar 4 at 6:22
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Your third type of angiosperm could be a primitive angiosperm, aka basal angiosperm. Monocots and most dicots share a common ancestor, and this primitive angiosperm diverged from that line before monocots evolved. The primitive angiosperm will have some characteristics of monocots and some characteristics of dicots.

From http://www.plantcell.org/content/20/9/2471

angiosperm evolution

These organisms exist. They are called basal angiosperms because they are thought to be like the primitive ancestors of monocots and dicots. A good example is order Nymphaeaceae, the water lilies.

enter image description here

Here is a nice table summarizing the characteristics that interest you. I found it at https://ucmp.berkeley.edu/glossary/gloss8/monocotdicot.html

table

For the water lilies, here are the characteristics. I labeled each with an M or D to show which category it is more like.

Embryo with 2 cotyledons fused into one (M+D) Pollen with single pore (M) Flower in multiples of three, or many. (?) Leaf veins reticulated (D) Vascular bundles scattered (M) Roots develop from radicle (D) Lack secondary growth (M)

So a mix of characteristics. There are other basal angiosperms but water lilies are good one for this. They are worldwide and live submerged / partly submerged in freshwater. They are wind pollinated or beetle pollinated.

Maybe since this is Worldbuilding you want something fictional. Well, purely aquatic habitats seems challenging for vascular plants. You could imagine an ancient angiosperm that somehow managed to deal with first brackish then salt water. These huge water lilies form forests like the kelp forests.

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  • $\begingroup$ That still doesn't answer the question. I specifically said "not the same as the other two." $\endgroup$ – JohnWDailey Mar 4 at 0:51
  • $\begingroup$ It shares characteristics with the monocots and dicots because it is an angiosperm. If your requested plant is an angiosperm, doesn't it need recognizable angiosperm characteristics? If it is enough to assert that a thing is an angiosperm but have not characteristic be anything like existing angiosperms, let me know because I will post for you the Pink Bunkadoo - 600 feet high, bright red, smells terrible. $\endgroup$ – Willk Mar 4 at 0:58
  • $\begingroup$ An angiosperm is just a closed seed. $\endgroup$ – JohnWDailey Mar 4 at 1:10
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    $\begingroup$ @JohnWDailey this answer clearly gives an example of what a plant group which is neither dicot nor monocot could look like - with some intermediate features, some unique features, and some features shared with one group or the other. It is a group which is "not the same as the other two". It also gives you the conditions where this group could thrive. Even If you really must have a group that differs in all of the five particulars you listed for the sake of it, this answer gives you something to work from (e.g. fused cotelydons, high petal numbers). $\endgroup$ – user42528 Mar 4 at 9:23
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  • Monocot: Simple structure.
  • Dicot: More complex structure.
  • Newcot: Fractal structure.

You can see the start of this in dicots. leaf veins have the start of some degree of self similarity.

Key factors of a more fractal structure will be increased self similarity at smaller scales.

Consider those big electrical metal towers. The early ones had heavy 4" right angle struts for the corner pieces, and a smaller one used for cross braces. Now there are about 4-5 sizes of braces. The braces have braces. And those braces have braces.

Complexity has increased, while weight of metal has decreased.

A fractal plant will have more leaf area per pound of plant. The one that comes to mind right now is asparagus.

Look at baneberry: It has thrice compound leaves -- a good example of fractal growth.

Evolution is a slow process.

I don't know that this will be the next Big Thing in Plants.

Whatever the next step is, it will become popular because it gives some serious advantage to that plant.

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    $\begingroup$ Please expand your answer, could you tell us how the fractal structure might look in two, three and four dimensions (ie over time)? Which would be answering the question as written. At the moment your answer is too brief. From review. $\endgroup$ – We are Monica. Mar 10 at 4:35

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