Carolyn Kunin: "...Quercus (oak) and chat. do indeed refer to the learned cat who day and night walks around the oak tree, first to the left and then to the right. / Ruslan and Liudmilla -- first few lines.
On seashore far a greenoak towers,
And to it with a gold chain bound,
A .learned cat whiles away the hours
By walking slowly round and round.
To right he walks, and sings a ditty;
To left he walks, and tells a tale....
[ ] Somethings are never abbreviated and botanical names, I believe (could be wrong)are among them. So chat. referring to Chateaubriand would not be correct botanical Latin. It would be Chateaubriandiensis, meaning he was the one that discovered the Quercus ruslanicus.

Here's an extract from ADA with an unrelated Chateaubriand,:entomologist, and François-René Chateaubriand (born in St. Malo)writing about "du grand chêne a Tagne"...
"During the last week of July, there emerged, with diabolical regularity, the female of Chateaubriand’s mosquito, Chateaubriand (Charles), who had not been the first to be bitten by it but the first to bottle the offender...The Boston Entomologist for August, quick work, 1840.. was not related to the great poet and memoirist born between Paris and Tagne (as he’d better, said Ada, who liked crossing orchids).
Mon enfant, ma sœur,
Songe à l’épaisseur
Du grand chêne a Tagne;
Songe à la montagne,
Songe à la douceur —
— of scraping with one’s claws or nails the spots visited by that fluffy-footed insect characterized by an insatiable and reckless appetite for Ada’s and Ardelia’s, Lucette’s and Lucile’s (multiplied by the itch) blood."

And, at various places, there's the Bryant castle (Chateaubriand) and St.Malo songs, and incestuous siblings, and Mlle La Rivière's "Enfants Maudits" There's even more verse: "My sister, you remember still/The spreading oak tree and my hill? // Oh! Oh! qui me rendra mon Aline/ Et le grand chêne et ma colline?/ Oh, who will give me back my Kill/ And the big oak tree and my hill?"

"...the orchids came from Demon who preferred to stay by the sea, his dark-blue great-grandmother.’
go down, and bury or burn this album at once, girl. Right?
‘Right,’ answered Ada. ‘Destroy and forget. But we still have an hour before tea.’
Re the ‘dark-blue’ allusion, left hanging:"

Particularly if compared with the ultramarine goings on in Proust's Guermantes: :"Van could not help feeling esthetically moved by the velvet background he was always able to distinguish as a comforting, omnipresent summer sky through the black foliage of the family tree. In later years he had never been able to reread Proust (as he had never been able to enjoy again the perfumed gum of Turkish paste) without a roll-wave of surfeit and a rasp of gravelly heartburn; yet his favorite purple passage remained the one concerning the name ‘Guermantes,’ with whose hue his adjacent ultramarine merged in the prism of his mind, pleasantly teasing Van’s artistic vanity." .