This is a list of Qenya words having to do with plants, compiled by David Salo on the basis of Tolkien's earliest Elvish wordlist, the "Qenya Lexicon" of 1915. David also provided the Latin names.
Many of these words don't look too bad in a mature Quenya context, at least as far as phonology goes. (For "ivy" we must prefer etil to etl.) The spelling is not that of mature Quenya, though: for q Tolkien later substituted qu (cf. the name of the language itself!), and in LotR at least, he also used c instead of k.
Flowers
ailinon: water-lily (fam. Nymphaeaceae)
fumella: poppy (Papaver sp.); fúmello valinórea: large poppy (Papaver sp.); kamillo fúmelot: poppy (Papaver sp.)
helilokte: wisteria, 'purple cluster' (Wisteria sp.)
helin: pansy (Viola tricolor)
helinille: violet (Viola sp.)
kamillo: large poppy (Papaver sp.)
kamilot: red clover (Trifolium sp.)
kampilosse: the wild rose (Rosa sp.)
kankale-malina: daffodil, 'yellow laughter' (Narcissus sp.)
losse or losille: rose (Rosa sp.)
narwe: sweet lily (Lilium sp.)
nénu: yellow water-lily
nieninqe: snowdrop 'white tear' (Galanthus nivalis)
qinqenna: Solomon's seal (Polygonatum sp.)
qiqilla: lily-of-the-valley (Convallaria majalis)
Trees
aiqaire: fir or pine; also súke (Abies sp. or Pinus sp.)
alalme: elm-tree (Ulmus sp.)
ektar: thorn or hawthorn (Crataegus sp.)
hóre: pine, stone pine (Pinus sp.)
kottule or kotulwe: hazel (Corylus sp.)
lindelokte: laburnum, 'singing-cluster' (Laburnum sp.)
mapalin: plane or sycamore (Platanus sp. or Acer pseudoplatanus)
mapalin varivoite: foreign mapalin, plane
mapalin fatsevoite: tasselled mapalin, plane
mapalin rámavoite: winged mapalin, sycamore
mapalin tarukka: horned mapalin, sycamore
mapalin wilwarinda: butterfly-like mapalin, sycamore
marinne or marinde: a fruit tree
mavoisi or alda mavoite: the chestnut-tree (Castanea sp.)
mavoisi tapatenda: the Spanish chestnut (Castanea sativa)
neldor or neldorin: the beech-tree (Fagus sp.)
nor or norne: the oak-tree (Quercus sp.)
palapapte: plane or sycamore, mapalin (Platanus sp. or Acer pseudoplatanus)
pinektar or pipinektar: hawthorn or whitethorn (Crataegus sp.)
piosenna: the holly-tree (Ilex sp.)
silqeléni: the silver birch, the long-tressed lady (Betula sp.)
silwin: the birch-tree (Betula sp.)
siqilisse: weeping-willow (Salix babylonica)
súke: pine or fir, trees bearing resin; also aiqaire (Abies sp. or Pinus sp.)
tamuril: yew-tree (Taxus sp.)
tarasse: hawthorn (Crataegus sp.); cf. ektar and pinektar tasarin: willow-tree (Salix sp.)
tyulusse: poplar (Populus sp.)
ulwe or uluswe: the alder (Alnus sp.)
vine or vinne: any conifer
Fruits and Berries
aipio: cherry (ai-pio 'holy berry') (Prunus sp.)
kampin: hips, the berries of the wild rose (Rosa sp.)
kolosta: cucumber (Cucumis sativus)
kulmarin: ?orange (Citrus sp.)
marin: fruits like the apple, with firm pulp and many seeds (Malus sp.)
melpo: fruits like a gooseberry, with squashy pulp and many seeds (Ribes sp.)
pio: fruits like cherries and plums, with firm pulp and a single stone (Prunus sp.)
piopin or pipin: haws, the fruit of the hawthorn (Crataegus sp.)
piukka: the blackberry (Rubus sp.)
Other plants
eldasilqe: maidenhair fern, 'elvish tress' (Adiantium sp.)
etl or etil: ivy (Hedera helix)
felpa: seaweed
fen: reed
filqe or filinqe or filimpe: fern (ord. Filicales)
inwetelumbe: mushroom. 'fairy-canopy' (clas. Basidiomycetes)
líne: cotton (thread) (Gossypium sp.)
liske: reeds
orikon: heather (Calluna vulgaris)
orivaine: pea (Pisum sativum)
pole: oats (Avena sativa)
telumbe: mushroom. 'canopy' (clas. Basidiomycetes)