Alder is an occasionally-used name that derives from an old English surname and also might refer to the alder tree, whose wood is used to make electric guitars.

Alder

Althea is a poetic, almost ethereal name found in Greek myth and pastoral poetry, associated in modern times with the great tennis player Althea Gibson, the first African-American to win at Wimbledon. 
 
Althea appears in Greek mythology as the mother of the hero Meleager and was revived by the seventeenth-century poet Richard Lovelace as a poetic pseudonym for his beloved.
 
These days, parents would also appreciate the short form Thea.
 
Althea is the most common girl name in the Philippines.

Althea

This pretty name is most commonly used in Southeast Asia, although Westerners might recognize it as the middle name of Owen Wilson's daughter Lyla.

Aranya

Arden is a gender-neutral name that's sleek and stylish but always seems to bob just below the surface of popularity, despite ticking all the boxes with its fashionable two-syllable, N-ending shape and its awesome nature-inspired meanings. In the 2021 US statistics, 41 percent of the babies named Arden were boys to 59 percent girls.

 A locational surname name deriving from several places in England, there are multiple legitimate derivations for this name. One is from Old English earn "eagle" + denu "valley", while another is from the Celtic ard meaning "high".

 For literature lovers: Arden is the name of the magical forest in Shakespeare's As You Like It (Shakespeare's mother's name was Mary Arden), and it also appears in the name and titular character of a poem by Tennyson, Enoch Arden.

Arden

Aspen is part of two groups of stylish and unique baby names: <a href="https://nameberry.com/list/329/nature-baby-names">nature names</a> and place-names. The name of a graceful tree in the poplar family with heart-shaped leaves so delicate they quiver in the gentlest breeze, Aspen is also the name of a trendy Colorado ski resort. Aspen started as a unisex name possibility but now is much more frequently worn by girls.
 Aspen entered the popularity list in 1993 and is a good bet to start climbing higher as more and more parents respond to the appealing place and nature image it evokes.

Aspen

Family surname or feminist statement name? Either way, this literary surname has a cool, current sound.

Atwood

Aveline is a name that's long been an obscure cousin of more widely-used choices, but may come into its own riding the tail of the megapopular Ava, which may derive from the same root.

 Although Aveline is a cognate of the French word for "hazlenut", the name actually derives from an obscure Germanic root, the meaning of which is not clear. Theories include "desired, wished for" and "water, island".
 
Aveline is different enough to sound distinct, but be warned: You will forever be explaining that no, it's not Adeline, not Evelyn, and so on.

Aveline

Aase 

Adoette

Amadahy

Ardian

Arinniti

Arwood

Asiza

A busby is the English name for the fur military headdress originally worn by the Hungarian hussars. As a first name, Busby is also the <a href="https://nameberry.com/list/317/unique-baby-names">unique name</a> of iconic movie choreographer Busby Berkeley.

Busby

Berewold

A beaming, friendly Irish last-name-first-name waiting to be discovered. 

Calhoun

Fresh and fragrant nature name more apt to be used for a boy. 

Cedar

Codrin

Codru

Collingwood

Dera

Dresden

An Anglo-Saxon name borne by the queen of Alfred the Great. American novelist Helen Ricker wrote under the pen-name Elswyth Thane. Variants include Elswith, Ealswith and Ealhswith.

Elswyth

Highly unusual water name -- and actor Colin surname -- with a Scottish burr.  Firth derives from the Old Norse word fjord.

Firth

Forester

Foster is one commonly heard last name that makes a fine first. The word foster means "to nourish" — as in "fostering hope", or "fostering a relationship". The only problem with Foster might be its association with "foster child."
 There are numerous notable last-named Fosters, including composer Stephen, actresses Jodie and Sutton, architect Norman, and comic strip artist Hal, creator of "Prince Valiant."

Foster

Though TV's "Frasier" made the name famous, and Frazier is a well-used variation, Fraser is the original, used mostly in Scotland. 

Fraser

Fujimori

Hanarin

Harosheth

Hartwood

Hayashi

Hurste

Izadi

This lively Old Testament nature name (belonging to one of the three beautiful daughters of Job) may be missing from the current US Top 1000 list, but it ranks highly here on Nameberry — making it one to watch! Also spelled KeziaH, the name has multiple legitimate pronunciations — from "KEE-szhah" to "KEZ-ee-ah" to "keh-ZYE-ah" — and comes complete with the sweet and sparky nickname Kizzy. A related name is the lovely cinnamon-scented Cassia, which beginning to be discovered by lovers of the fashionable Cas- clan.

Kezia

Kashi

Keita

Linwood

Linbei

Marwood

Mavka

Moriko

Nahele

Northwood

An unusual-sounding name used in Basque-speaking parts of France and Spain.

Oihan

Despite the success of so many O-starting <a href="https://nameberry.com/boys-names">boys names</a>--Oliver, Owen, Otis, Oscar--Oswald has not yet shown any signs of resurrection, though he does have the animating nicknames Ozzie/Ozzy and Oz. The name has some literary cred--in Chaucer's Canterbury Tales, Shakespeare's King Lear and a novel by H. G.Wells--and there was early cartoon character Oswald the Lucky Rabbit.

Oswald

A grassy place with trees is a nice image to attach to a name. 

Park

Perrie

Phraiwan

The list of occupational boys' names continues to expand, and this is one of the latest to ride onto the range. And, as trends collide, it also has the popular western, cowboyish feel. A much better choice than the increasingly (and scarily) heard Danger.

Ranger

Fairly popular a hundred years ago but out of sight now, the quirky Roscoe deserves a place on every adventurous baby-namer's long list. It joins Rufus, Roman, Remy, Romulus, and Ray as one of the R names that sound fresh again after too many years of Robert, Richard, and Ronald.
Originally a place and surname, Roscoe had its glory days in the 1880s, when it reached as high as Number 138, then gradually declined, possibly damaged by the scandals surrounding silent star Roscoe "Fatty" Arbuckle, and then the hillbilly image it acquired thanks to Sheriff Coltrane on The Dukes of Hazzard. 
Roscoe has been out of the Top 1000 since 1978 but feels very much in step with the trending o-ending boy names popular now, such as Milo, Hugo, and Otto.
Trivia tidbit: The R in Edward R. Murrow stands for Roscoe; the distinguished newsman's first name was really Egbert.

Roscoe

Reniala

Rinji

Riodhr

Woodsy name referring to the Roman tree god Silvanus. 

Silvain

Sylva

Sylvaine

One of the many variations of Silvanus, the name of the Roman forest god, and a little-used member of the freshly stylish Sylv- family of names. Silvan is the sleek German and Dutch form.

Sylvan

Sylvana

Sylvanus or Silvanus was the Roman god of the forest whose name is much more often found today in such variations as Sylvia, Sylvie and even Silas than in its original form. But if you're looking for a genuine mythological or Ancient Roman name with a nature connection, this might be the perfect choice.

Sylvanus

The musical, sylvan Sylvia seems poised to join former friends Frances and Beatrice and Dorothy back in the nursery.
 Sylvia has been consistently on the popularity list since records started being kept. She was a Top 100 name from 1932 to 1948, reaching a high of Number 48 in 1932.
 Spelled Silvia, she was the mother of the twins Remus and Romulus, who were the mythological founders of Rome, and was a character in Shakespeare's Two Gentlemen of Verona. The Bard also penned the immortal lines "Who is Silvia? what is she, that all our swains admire her?" -- words echoed in the Edward Albee play The Goat, or Who is Sylvia?
 Sylvias have also played major roles in Clare Booth Luce's classic play The Women and the Fellini film La Dolce Vita.
 Sylvia Plath was the Tragic Heroine of modern poetry.
 The French Sylvie is an appealing alternative.

Sylvia

Although Sylvia seems to be having somewhat of a revival among trendsetting baby namers, we'd still opt for the even gentler and more unusual Sylvie. Despite being dated in its native France (where it was popular during the 1950s and 60s), in English-speaking regions it still feels fresh and international without being unfamiliar and has a cosmopolitan, international air. It debuted on the US Top 1000 in 2016.
 Jason Bateman chose it as the middle name of his daughter Maple. In one of Lewis Carroll's lesser known novels, Sylvie and Bruno, Lady Sylvie is the princess of Fairyland.

Sylvie

Seda

Silverius

Sylvanella

Tallis

Tallys

Upwood

This waspy name on the rise for boys, hasn't hit yet for girls, but could join others, like Sawyer, that have.


Walker

Winswood

Witimer

Sounds like the name of a new synthetic fabric. 

Xylon

Yardley is an English surname with a distinguished vibe, a la Chauncey and Clancy. Extremely rare for either sex, it would make a stand-out choice that still fits in with current trends.

Yardley

Zhaosen

mangoslushie's list "forest-related names for nemophilists" of 76 great name ideas: Alder - Zhaosen!