Maybe I can set this in type as the reverse side of the map - haven't decided yet.
In the Year of Accounting 1670, now being two hundred forty-one years since the botanophasists loosed upon our continent their various wonderful and despicable botanical constructs. The beet-vine, the alorphous kelp, the nitty tuber, the unquenchable nutshrub; these have made us what we are today, for better or worse, and these power the very conflicts that seem to threaten our way of life. But no! Threatening? T'is indeed the core of our way, the Civilized Alternative to the old path, the Newer and Better methodology which permits vast swaths of heretofore impenetrable wastelands to be Productive, yea verily even Verdant to the point of Overflowing!
Our forefathers avoided these plains at the heart of our land - they alternated impenetrable swamp with shallow sea laced with venomous fish, tangled jungle with bleak expanses of lifeless rock. Then, as now, mankind clung to the verge; the mountains and hills of Clane, of Stolvin, of Mizin-diu. But then we thinking denizens were but few and fur-clad, limited to hunting or being hunted, in bands scarce worthy of the title "tribe".
Then came Dr. Motricas, Professora di Nivalienna, The Old Stalwart, Gontoris the Wise, and of course, Juan the Lean. These and their minions, travelers from the lands of the beyondsea, brought us wondrous botanical arts, and forever altered the whole of life here upon The Chiconna. Now, there are those who say this place was better off without manmade plants and the vast efforts it requires to keep them in check. But Woe! Woe would be our lot! Had we no Great Struggle with the Tubers of Doom, would we have bred the Hares of Januvember? Had we no Exploding Vines would we ever have devised our railways, our dirigibles, our manufactories and street-lamps powered by methane, by alcohol, lifted by hydrogen? Would indeed we have found the uses for nitrates in the exploding arts, or the fertilizing sciences? Would not the mosquito and the piranha have ruled the interior of The Chiconna, and where would be the myriad millions of our citizens? Would the music of Eleanor the Vibrant ever have arisen? The philosophies of Stricknard or Bunstdt? The sweet mercies of The Faith and The Knowing - at odds though they be yet richer by them both we are?
And now, striving to be the primary among many, each of our Nations goes out to war on the Plains - going out to contend, indeed going Away, that our homes may not be in peril. How inconceivable it is, we are told of those strange folk beyondsea, that battles could occur among ones' cities; that wars could devastate industry and agriculture, that fighting and civilization mingle to the point of the former endangering the latter. What horror! May it never be so, here!
And in support of that Right and Proper way, we the Forecasters of the Plains of Belicas, based in the Eternally Neutral City of Jiencorre, Oasis of Jiencorre, Grand Duchy of Jiencorre, by the grace of His Most Puissant Joachin XIV, Grand Duke of the Hill of Jiencorre, etc, do hereby publish and promote this Forecast for the conditions conducive or restrictive to the ends of warfare, across the whole of the Chiconna Interior and the Bay of Doneashthort. May the best army win the day, and may considerable resources of the botanical riot hereabouts be diminished, harnessed, and converted, to the benefit of humanity and preservation of civilization, to the advancement of science and the perfection of engineering, to the support of The Faith(s) and the Learned, Amen.
These folks do their warfare away from home, in a steam-powered mechanically intensive way, with mobile harvester/ chem plant/ distillery/ refinery units quite literally living off the land. Hydrogen as a fuel is tough to transport - these folks' pressure vessels are fragile, and fiery accidents abound.
On the one hand, it takes a degree of yearly harvest havoc to sufficiently blunt the botanical ambition of the plant world across this plain, lest the equivalent of Kudzu With Bad Attitude take over their highland homes and probably expand overseas. Their precautionary prophecies tell of a world covered in choking green, with humans diminished to a scampering species much like squirrels. All their art and science are turned to harvest and use of the plants, yet conversely they must maintain the stuff at some degree or perish. This continent has no petrol, at least none these folks have discovered. There's coal, but it's deep and hazardous to mine; the few deposits reachable by their technology are one cause for the wars they continually conduct. Steam runs their wheels and gas lights their homes, and their young either march off to war or build ever more intricate devices to do battle -- first with the plants, and only incidentally with the rival nations.
The climate was the enemy even before the botanophasists showed up with their lab-born demons-of-chlorophyl. Some years the tides rise higher, and the mudflats become kelp(ish) beds. Rain torrents pass through daily, but then sweltering sun cranks the humidity up to 99.44%. Swamps breed methane-lit fungi that the local reptiles and amphibians consume... heartburn is a real thing when dining on the Splindiferous Crocodilian, or the FrogBombs of the Mirey Marshes. A benefit of the man-spawned botany is that mosquitos are all but extinct... the pseudo-piranhas eat their larvae, and the vampiric bats lunch on any that take flight. But really, the constant film of hydrocarbons that gives such a delightful otherworldly sheen to marsh and pond alike stops the skeeters before they even hatch. What a benefit. Wetlands that can be lit afire, but which harbor no malaria. Geniuses I tell you, geniuses they were!
The aesthetic of the map's margin illustrations is a bit modern, just because I had few period pix to work with. This isn't Earth's steampunk, but some other world's; who's to say that bit of GMC Truck visage isn't their 1890 look? :-) I am no artist, so I patched together bits of refinery and distillery photos, with tank treads and of course the required dirigible. The bits that aren't outright public domain were as follows:
Attribution license - refinery from Wikimedia Commons, source
Flickr: keepitsurreal's Photostream Kyle Pearce
Sinclair Refinery Wikimedia Commons attribution license
Flickr: charkesw Charles Willgren
Tank tread creative commons attribution license
Flickr: Rennett Stowe Rennett Stowe
Whew! All that to set the stage... now to the actual map. Don't get your hopes up - this has to be a diagrammatic thing not unlike our weather maps - even if I had time to do up an appropriately complex affair, I probably couldn't carry out the doing of it. <Shrug>... t'is steampunk 'cause I say so, and 'cause the background makes it so :-).