Currently, all alchemy surveys that drop are only for "flowers" (Columbine, Wormwood, Corn Flower, Bugloss, Blessed Thistle, Mountain Flower, Lady's Smock & Dragonthorn) While these tend to be the more valuable of rewards, due to their usage in well used potions (Tri-pots, Mag and Stam pots), there is a dearth of other materials that are used in Alchemy writs, with no comparable survey source.

My suggestion is as follows.
In zones that have 3 versions of Alchemy surveys (Craglorn & Wrothgar) 2 of the three are converted to alchemy surveys of other types
The I version stays the same
The II version becomes a "Fungi survey" that can drop Violet Coprinus, Emetic Russula, Imp Stool, Luminous Russula, Namira's Rot, White Cap, Stinkhorn
The III version becomes an "Animal Parts survey" that can drop Fleshfly Larva, Mudcrab Chitin, Scrib Jelly, Spider Eggs, Torchbug Thorax, Butterfly Wing, Beetle Scuttle

For the base game zones:
Zones 1, 2 and 3 in each alliance stays the same
Zone 4 (Eastmarch, Alik'r & Malabal Tor) converts to a "Fungi Survey"
Zone 5 (The Rift, Bangkorai, Reaper's March) coverts to a "Animal Parts survey"
The two in Coldharbour convert to 1 each of a "Fungi" and an "Animal Parts" surveys

For the Chapter Zones
Vvardenfell stays the same
Summerset - Surveys are added (why are there none here?) and the Alchemy one is a "Fungi Survey"
N. Elsweyr - Alchemy survey is converted to an "Animal Parts survey"

New chapter zones will have surveys added, and they go in rotation above, so Greymoor will be a standard Alchemy survey.

This will continue to have that the majority of surveys are still those with flowers, since those are used mostly, but that there are some surveys that are different, without locking any of them behind DLC content exclusively. There would also not be any more surveys added (other than in Summerset), as there are already a plethora of different ones)

(I'd also suggest that Nirnroot be added to the "Fungi Surveys" and that Water Hyacinth is added to the "flower" surveys)