Below are a number of terms which are commonly used when describing colors in plants.
ALBA (AL-bah) - White.
ALBICANT (AL-bi-kant) - Growing or becoming white.
ALBIDO (al-BEE-doe) - Whitish.
ALBIDO-FULVUS (al-BEE-doe-FUL-vus) - Yellow and white.
ALBIFLORUS (al-bi-FLOR-us) - White-flowered.
ALBINISM (AL-bi-NIZ-m) - Lack of normal coloration in a plant.
ALBINISTIC (AL-bi-NIZ-tik) - Afflicted with albinism.
ALBO-STRIATED (al-bo-STRY-ated-ed) - Striped with white.
ALBUS (AL-bus) - White.
AMETHYSTINE (AM-e-THIS-tin) - Pale violet color.
AMETHYSTOGLOSSUS - (am-a-thiss-to-GLOSS-us) Having an amethyst colored lip.
AEGENTINE (argentus) (ar-jen-teen) - silvery.
ARMENIACEOUS (ARMENIACUS) (ar-MEN-i-a-shus) - Apricot color.
ATRATUS (at-RAY-tus) - Blackish.
ATRO (AT-roh) - Meaning dark.
ATROPURPUREUS (at-ro-pur-PURE-ee-us) - Dark purple.
ATRO-RUBENS (at-ro-ROO-bens) - Deep reddish.
ATROSANGUINEUS (at-ro-SAN-gwin-e-us) - Deep blood red.
ATRO-VIRENS (at-ro-VYE-rens) - Dark green.
AURANTIACUS (au-RAN-ti-ay-kus! or o-ran-SHI-a-kus) - Orange colored.
AUREO-FLAVUS (aw-ree-o-FLAY-vus) - Golden yellow.
AUREO-MACULATA (aw-ree-o-mac-kew-LAY-ta) - Gold spotted.
AUREO-MARGENATA (aw-ree-o-marj-i-NAY-at) - Golden margined.
AUREO-RETICULATA (aw-ree-o-re-tick-yew-LAY-at) - With golden veins.
AUREO-VARIEGATA (aw-ree-o-vair-ee-i-GAY-at) - With golden markings.
AUREUS (AW-ree-us) - Gold colored.
BLUSH (or FLUSH) - Refers to a different color overlay of the base color of a flower, i.e. a red blush.
CAERULESCENS (cee-ROO-le-sens) - Having a tendency to blue.
CAERULEUS (cee-ROO-lee-us) - Bright or sky blue.
CAESIOUS (SEE-shi-us) - Bluish gray.
CARNEUS or CARNEOUS (CARE-ne-us) - Flesh-colored.
CERIMUS (SEE-re-mus) - Wax-colored.
CHLORANTHUS (klo-RAN-thus) - Having greenish-yellow flowers.
CHLOROCHILUS (klo-ro-KY-lus) - Green-lipped.
CHLOROPS (KLO-rops) - Pale green.
CHRYSANTHUS (kris-SAN-thus) - Golden-flowered.
CHRYSOCREPIS (kris-so-CREEP-is) - Golden shoed.
CHRYSOS (KRI-sose) - In Greek compounds, signifying gold or golden yellow.
CHRYSOTHYRSUS (kris-so-THUR-sus) - Golden racemed; a thyrse of golden flowers.
CHRYSOTIS (KRIS-o-tis) - Golden eared.
CHRYSOTOXUS (kris-o-TOX-us) - Golden arched.
CINNABARINUS (SIN-a-ba-RIN-us) - Vermilion-colored.
CITRINUS (SI-tri-nus) - Lemon-colored.
COCCINEUS (ko-sin-e-us) - bright scarlet.
CONCOLOR (KON-color) - Uniformity of hue in sepals and petals.
CRETACEUS (kree-TAY-shus) - Chalky white.
CRUENTUS (KREW-en-tus) - Blood colored; or with blood colored spots.
CUPREOUS (KEW-pre-us) - Copper colored.
CYANEUS (si-AY-ne-us) - Bright blue; azure.
DICHROMUS (DYE-kro-mus) - Two-colored.
DIXANTHUS (di-ZAN-thus) - Having flowers of two shades of yellow.
ERUBESCENS (ER-roo-BES-ens) - Blushing, glowing rosy red.
FERRUGINOUS (fe-ROO-ji-nus) - Rust colored.
FLAVESCENS (fIa-VES-ens) - Yellowish.
FLAVIDUS (flay-VI-dus) - Yellow.
FLAVOUS or FLAVUS (FLAY-vus) - Yellow.
FLUSH - see blush.
FULVOUS (FUL-vus) - Tawny; dull yellow, with mixture of gray and brown.
FUSCATUS (fuss-KAY-tus) - Brownish.
FUSCESCENS (few-SES-ens) - Reddish brown.
HAEMATOCHILUS (HEE-ma-toe-kye-lus) - Bloody-lipped.
LEOPARDINUS (LEP-ard-in-us) - Tawny or spotted like a leopard.
LEUCOCHILUS (LOO-ko-ki-lus) - White-lipped.
LEUCORRHODUS (loo-koh-ROH-dus) - Rosy white.
LIMBATE (lim-BATE) - Bordered, one color surrounded by an edging of another.
LURIDUS (LEW-rid-us) - Yellowish brown.
LUTEOLUS (LEW-tee-O-LUS) - Pale yellow.
LUTEO-PURPUREUS (Lew-TEE-o-pur-POO-re-us) - Yellowish purple or yellow and purple.
LUTESCENS (lew-TES-ens) - Yellowish.
MINIATUS (min-i-AY-tus) - Vermilion-colored.
NIGER (NYE-jer) - Black.
NIGRA (NYE-gra) - Black.
NIGRESCENS (nye-GRES-ens) - Blackish.
NIVALIS (NI-val-is) - Snowy white.
OCHRACEOUS (o-KRAY-shus) - Yellowish.
OCHROOID (OH-kroid) - Yellow ochre in color.
PALLIDUS (PAL-i-dus) - Pale.
PHENICIAN (fee-NiSH-an) - Purple red.
PHOENICEUS (See PHENICIAN)
PURPURASCENS (pur-poo-RAY-sens) - Becoming or turning purple.
PURPURATUS (pur-poo-RAY-tus) - Marked with purple so as to have a certain regal quality.
PURPUREUS (pur-PEW-ree-us) - Purple.
PURUS (POOR-us) - Spotless; of one color.
QUADRICOLOR (KWAD-ri-col-er) - Four-colored.
QUINQUEVULNERUS (kwin-kwe-VUL-ner-ose) - having five wounds, or blood-red spots.
RUBER, RUBRA or RUBRUM (ROO-ber) - Red.
RUBESCENS (ROO-be-sens) - Rosy-red; suffused with rose; blushing.
RUBRIC (ROO-brik) - Colored in or marked with red.
RUBRO-OCULATUS (ROO-bro-OK-yew-lay-tus) - Red-eyed.
RUFESCENS (roo-FES-ens) - Reddish brown.
RUFOUS (ROO-fus) - Reddish brown; rust colored.
SANGUINEUS (san-GWIN-ee-us) - Blood-colored.
SANGUINOLENS (san-GWIN-o-lens) - Approaching blood-color.
SANGUINOLENTUS (san-gwin-o-LENT-us) - Having blood red spots or veins.
SEMI-ALBA (se-my-AL-bah) - Term applied to white flowers which have a colored lip.
STRAMINEOUS - straw colored
SULPHUREUS (sul-FEW-re-us) - Sulphur-colored; light yellow.
TESTACEOUS (tes-TAY-shus) - Of a brick red or brownish red color.
VARIEGATED (VAY-ri-e-GATE-ed) - Irregularly colored in patches, blotched.
VARIEGATION (VAY-ri-e-GAY-shun) - Condition normal to certain plants where the over-all green tissue of leaves is broken by areas of paler green or white or other color. Conceived as a result of somatic mutation of the chloroplasts.
VIOLACEUS (vi-o-LAY-shus) - Violet-colored.
VIRGINALIS (vir-jin-AL-is) - Maidenly, pure white.
VIRIDESCENS (vi-ri-DES-ens) - Becoming green.
VIRIDIPURPUREUS (vir-id-i-pur-PUR-i-us) - Greenish purple.
VIRIDIS (vir-ID-iz) - Green or bluish green.
VITELLINUS (vi-TEL-in-us) - The color of an egg yolk.
XANTH (zanth) - Yellow.
XANTHIMUS (ZAN-thim-us) - Yellowish, amber.
XANTHO - Prefix, yellow colored.
XANTHOCHROMIC (zan-thow-I-KROH-mik) - Turning yellow.
XANTHODON - yellow toothed.
XANTHOPHYLLUS - yellow leaved, etc.
XANTHOPLEBIOUS - yellow veined.