Dreamflowers and Lotus-eaters.

Upon meeting Merry and Pippin, Treebeard exchanges names with them. As he does so, he teaches them about the connection between the name of a thing and its history. Since in his language "real names tell you the story of the things they belong to," names grow longer the longer the story goes on (TT 3.iv.465). Thus, Treebeard's real "name is growing all the time." 

When he later learns that Merry and Pippin got both into and out of Lothlórien, he is surprised. The reflections on Lothlórien he offers speak very much to his idea of how names work. 

"...Laurelindórenan! That is what the Elves used to call it, but now they make the name shorter: Lothlórien they call it. Perhaps they are right: maybe it is fading, not growing. Land of the Valley of Singing Gold, that was it, once upon a time. Now it is the Dreamflower. Ah well! But it is a queer place...." (3.iv.467, emphasis mine)

From Laurelindórenan to Lothlórien, from the Land of the Valley of Singing Gold to the Dreamflower, the name is becoming shorter when it should be growing longer. To him that makes it a "queer place," which may be fading rather than growing. Treebeard does not see this as a good sign. Yet he doesn't know the half of it. He does not know, apparently, that the name is now cut even shorter, to just Lórien, which he would know could be translated as "Dreamland" (“Lórien.” Parf Edhellen, https://www.elfdict.com/wt/502964). The Golden Wood is called Lórien twice as often by the characters and narrator as it is called Lothlórien.*

The first element in Lothlórien is loth-, which is Sindarin for flower or blossom (Quenya lóte). It may be that Tolkien is remembering something from his school days and working in an obscure philological allusion to a type of dreamland he encountered in Homer's Odyssey. In the Odyssey ix.80-104 Odysseus arrives in the land of the Lotus-Eaters (λωτοφάγοι/lotophagoi), where eating the fruit of the lotus/λωτός leaves his crew in a dreamlike, happy state. As Alfred Heubeck has observed, “the λωτός- plant, with its magical properties of suppressing the desire to return home, is symbolic of the insecurity of human existence poised precariously between the spheres of empirical reality and mythical unreality” (Heubeck et al. 18, emphasis mine).** 

Heubeck's assessment of the λωτός-plant's significance resonates rather eerily with Galadriel's words to the Company when they arrive in Lórien: "your Quest stands upon the edge of a knife. Stray but a little and it will fail, to the ruin of all. Yet hope remains while all the Company is true" (FR 2.vii.357). That Odysseus has to drag his companions back to the ship by force echoes Treebeard's surprise that Merry and Pippin "ever got out"  of Laurelindórenan (TT 3.iv.465). Faramir, who is the only other character in The Lord of the Rings to call the Golden Wood by the name Laurelindórenan, will later express his own surprise that Frodo and Sam had been there, citing ancient wisdom: "For it is perilous for mortal man to walk out of the world of this Sun, and few of old came thence unchanged, ’tis said" (TT 4.v.667).

So, did Tolkien derive the loth of Lothlórien from Greek? Perhaps, perhaps not. Yet it remains an intriguing convergence of sound, meaning, and context. 

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*Not counting the Prologue, Appendices, and Index, Lórien occurs 74 times and Lothlórien 37 times. Treebeard of course mostly calls it Laurelindórenan, and a couple of times Lothlórien, but never Lórien.

** Alfred Heubeck, et al. A Commentary On Homer's Odyssey. Vol. II: Books IX-XVI. Oxford University Press. 1990.