What base guidelines do I use if I want to create a new plant type, with no supernatural abilities, i.e. an oak tree that fruits strawberries, or a rosebush whose thorns are better shaped "nails"?
Secondly what guidelines are there for increasing the productive capacity of a plant-line. I.e. increasing the yield of oats/ barley by replicating intelligent breeding? I assume it is via craft magic, but I need some idea of the natural cap, and how adding magic can increase the cap, and if I can make the increased yeild/growth rate heritable.
First wait until 1900, if you plan to do it through craft magic since that is when technology to improve crop yields in any method other than improved crop rotation occurred.
Otherwise you might research fertility magic, or there may be a hedge tradition out there somewhere that could accomplish this with plants. Creo Herbem might manage it essentially from scratch with some extra levels of magnitude for unusual properties...
I know that grafting onto rootstocks was known to Romans, and breeding for animals was done lots and lots, so the knowledge is there in the paradigm about generalized inheritibilty, and that cross breeding can improve characteristics. Magic just has to speed that up.
I suppose to create, as one of the examples you give, a tree that grows strawberries, you would need to use a ritual CrHe spell to create an unnatural tree - you'd need to determine the level of that spell though.
I'm not sure but could you then get cuttings or seeds from this tree and grow them naturally? This seems a little gamey and I believe David Chart did say somewhere that unnatural things require magic to sustain their unnatural properties (no source, just a vague memory - someone with a better memory than me might help here)
Other than that - my suggestion would be have some fun experimenting with warping plants. I can see a long term project being undertaken by someone wanting to obtain a useful warping mutation - in a similar way to what we did IRL when we realized that we could use radiation to try and obtain useful mutations in plants (for reference look up 'mutation breeding') - this could, of course, also be a useful source for stories.
As always, this would definitely be something for the story guide and players to talk though as well, to ensure that it fits into the world as the troupe sees it.
I remember having a related debate on this board some years ago (I couldn't find it just now). I also didn't find any great quotes from the core book to support this. But I do agree, I think that the group needs to use some judgement in deciding what can and can't be permanently magically created with a creo spell. Assuming I won't find any other rules quote to support this position, I'd link it to the greater limit of essential nature. A magically created plant could be so unnatural that it violates the essential nature of being a plant and thus would need a continuing magical effect to support its existence.
(Not that a strawberry tree would fall into this category.)
If you need magic to sustain a magical plant you can "fix" this by growing the plant in a magic aura. Or by enchanting the soil so it will help sustain the magical tree.
I did read the entire thread backwards to find, that rgd20 didn't look for a strawberry tree, but for
Now which plants or animals can live and breed naturally in Mythic Europe, and which combinations of features violate The Limit of Essential Nature (ArM5 p.79f)? This is not cut and dried.
The Bibliotheca of Pseudo-Apollodorus lists the classical Chimaera, and was known and esteemed - at least by some scholars like Photios I - in the middle ages. But is that sufficient to make the Chimaera exist naturally in Mythic Europe, as an animal that breeds true? Or is Mount Chimaera rather a place with a strong, continuous Magic aura, and Chimaerae are Magic creatures subject to RoP:M p.52ff Acclimation? That's a SG decision.
Anyway, if a chimaera - plant or animal - is a Magic compound creature, I don't see, how it could just be Creo-ed with a ritual or Rego-crafted to survive and breed.
I was more looking to find inspiration as to where the limits of "natural" were, given as I said the well known practice of grafting trees onto different root stocks, and the great deal of knowledge of breeding animals to get desired characteristics.
I am going to start playing an Apple-gild Herbam Maga soon, and am looking to inprove the lot of mundanes, so I need stuff to improve agricultural yeilds/hardiness that will work out side magical Auras, and so I thought of how magic could be brought to bear to improve an otherwise mundane task. Fantasical bye-products would be accceptible for keeping in the covenant, but mundane increases are more interesting.
Take a look at the creation of broccoli for an example. Broccoli was created through selective breeding starting nearly two millennia before the typical saga time. Selective breeding wasn't just with animals.
Maga Monsanta, specializing on selective breeding of plants, has to have some Profession: Farmer to know what she is doing in general. And then she needs solid InHe and CrHe. The latter for TME p.41 A Harvest by Morning, so she can generate the result of her last cross-breeding attempt fast, and the former to gauge the potential of seeds and plants with spells based on ArM5 p.136 box Intellego Herbam GuidelinesLevel 4: "Learn all mundane properties of a plant ...".
No vis is needed, but the soil to grow the plants on should be protected from spies and curious mundanes. And her covenant needs to be prepared for handling estranged merchants, guilds and nobles, because improving seeds and crops can as easily make enemies as friends.
You can also get inspiration in Magi of Hermes, the Original research done by Marcus about creating what are essentially Chimeras.
Adjust the difficulty of the research, and follow the example. In term of Magic theory, it should follow the same approach: a mage is trying to create a living animal/plant that does not exist.
There is probably a third alternative by trying to enchant a plant, but here we are treading a more fuzzy patch since we start enchanting living beings, hich is not clearly defined in the rules - who controls the enchantments ? the enchanted being or the enchanter ? But they are precedents: enchanting tatoos or body part is possible (with the right mysteries), binding a familiar is a unique form of enchantment, and in Magi of Hermes, one mage enchanted a sapling as talisman, which then grew and became a walking tree.
So it is up to your group to decide how difficult you want to make it: a simple, minor breakthrough that would allow you to simply enchant a plant ? a more complexe research (like Marcus) ? There is no cannon rule to answer your question, but there are several options which are all possible as long as everybody agrees
