I found Karana's Begonia's at the following locations in EL. There's more than these but I think these will give you the most efficient route to harvest them:
This is the second quest in the Anashti Sul deity line. Plumetor Dul'Sadma wishes to resurrect the Seeress who was the original prophet of Rodcet Nife. To do this, you need to create a potion, and the components can be found within The Enchanted Lands.
Karana's Begonia
Collect 12 petals of Karana's Begonia. These appear to spawn near trees. They are a yellow flower, some near the docks, some towards the wasp nest, some over towards the seamist fae, some on the fae isle itself and there are a couple at the Runnyeye Ward. Reported loc's include:
27.87, 0.64, -32.23
76.52, -1.44, -47.97
167.28, -0.17, -94.23
241.84, 2.51, -154.79
217.72, 8.51, -273.41
167.21, 10.05, -433.69
164.13, -0.29, -475.71
136.18, 1.63, -522.51
53.75, -2.95, -183.78
33.36, -2.37, -164.94
-93.40, -1.63, -178.21
-123.53, -1.49, -7.25
Use the vial in the Lazy Drain. Head to -182.68, -5.21, -255.66 and use the thin glass vial that's in your inventory.
There will be 2 vials in your inventory. Make sure you have the right one!
Head to 469.24, 2.53, -388.35 and start killing the halflings around there. Be aware some of these are heroic. You need 10 updates.
When you are inside, head straight fowards, up the steps and down the steps directly opposite. Be aware there are level 32, double down, aggro mobs in here. Thankfully they can all be solo'ed. Once on the other side, you will see the body of Seeress Ealaynya Ithis. Right-click her to give her the potion, and then hail the nice, new undead version! She will tell you why Rodcet Nife returned, and then it's off to The Ruins of Varsoon to collect information. You can invis/stealth to these, but gathering the notes will break either of those abilities. They are in the following locations:
2 scrolls at -152.62, 6.25, 45.02
-60.28, 4.24, 5.33 (Beware: The named alchemist spawns here, and he -can- see through invis/stealth)
Now you need to find evidence of Bertoxxulous in Norrath. You will spot these greenmist-covered dirt mounds in The Thundering Steppes, anywhere undead are found. Some locations are:
Once you have 8, your next stop is Zek. Apparently, there are rumours of Bertoxxulous testing on orcs, so this is what you are sent to investigate. Just run around killing orcs for your update. You need 8 of them, and it appears to be uncommon, so this might take a while.
Anashti Sul has been confined to the Void for much of Norrath's history, and much has changed since her imprisonment. Notably, the appearance of Rodcet Nife as the new God of Life, and the rise of Bertoxxulous as the Lord of Disease. Since neither were among the gods when Anashti Sul was watching over Norrath, and they both have returned to Norrath only recently after a 500 year absence, it would be prudent to collect more information to present to Anashti Sul when she returns. In order to do that, I must gather more information on Rodcet Nife from the Seeress Ealaynya Ithis, and more information for Bertoxxulous from the Ruins of Varsoon.
Stage 1
I must first gather the materials to create the Gift of Waking Dream. I should be able to locate the necessary items within the fields of the Enchanted Lands.
Start:
I should collect the petals of Karana's begonia, a flower found in the Enchanted Lands.
Complete:
I have collected enough of the Karana's begonia petals.
Start:
I should use the thin glass vial that Plumetor Dul'Sadma gave me to collect water from the mouth of the Lazy Drain, where it enters the Enchanted Lands from Rivervale.
Complete:
I have collected a sample of the water from the Lazy Drain.
Start:
I will need the blood of the corrupted halflings, who are under the command of the Overseer. I should be able to find them in many areas throughout the Enchanted Lands.
Complete:
I was able to collect enough samples of corrupted halfling blood.
I have collected all of the items I needed to create the Gift of Waking Dream.
Stage 2
I will need to create the Gift of Waking Dream, and give it to the Seeress Ealaynya Ithis.
Start:
I should mix the ingredients of the Gift of Waking Dream using the rune adorned silver vial that Plumetor Dul'Sadma gave me.
Complete:
I have created the Gift of Waking Dream.
Start:
I will need to locate the Tomb of the Seeress, and administer the Gift of Waking Dream. I should search for an entrance outside the gates of Qeynos -- perhaps I can find a passage through one of the sewer grates.
Complete:
I have given the Seeress the Gift of Waking Dream, and she is now in the service of Anashti Sul.
Start:
I should speak to the Seeress about Rodcet Nife.
Complete:
I have gathered all of the information I will need on Rodcet Nife.
I have collected the information on Rodcet Nife.
Stage 3
I must collect more information on the Lord of Disease, Bertoxxulous.
Start:
I should look for information on Bertoxxulous in the Ruins of Varsoon. Perhaps finding notes or scrolls regarding his worship of Bertoxxulous would be useful.
Complete:
I have collected several pieces of information from within the Ruins of Varsoon.
Start:
I should find evidence of the influence of Bertoxxulous in Norrath. I might want to search the Thundering Steppes, as they were once infected by his power, and the very soil itself might still hold remnants of that curse.
Complete:
I have gathered several piles of residually infected dirt from within the Thundering Steppes.
Start:
I should find information on the current activities of Bertoxxulous. There are rumors of some manner of testing on orcs.
Complete:
I have collected enough inoculated orc blood.
I have collected enough information on Bertoxxulous.
Stage 4
I should return this information to Plumetor Dul'Sadma at the Sinking Sands dock.
Start:
I will need to take my findings back to Plumetor Dul'Sadma.
Complete:
I have turned over what I found to Plumetor Dul'Sadma.
I have provided the information to Plumetor Dul'Sadma.
I have gathered a fair amount of information for Plumetor Dul'Sadma, so that she might convey the knowledge to Anashti Sul during their communions. It appears that Rodcet Nife may be residing on the Plane of Health, which was once the home to Anashti Sul, and was, in fact, created by her. Although there is plenty to be done yet in preparation, I have earned a small rest while Plumetor Dul'Sadma sorts through the information I have brought her.