Abutilon eremitopetalum (endangered Hawaiian plant) - Alternating vowels and consonants.

Cytomegaloviruses - single word alternating vowels and consonants.

Euphausiacea (krill) - four pairs of vowels.

cimicid, cixiid, dixid (bedbug, planthopper, midge) - All Roman numerals for letters. (If you allow 'u', you can add Illicium, culicid (evergreen, mosquito).)

Armadillidiidae (pill bugs) - Nine consecutive Roman numeral letters. Bacillicidic (destructive to bacilli) has ten consecutive Roman numeral letters.

Fabaceae (legumes) - Letters are hexadecimal digits (A-F). (0xfabaceae = 4206546606.)

Fagaceae (beeches) - Letters are notes of the musical scale (A-G).

coccidiocide (destruction of parasititc coccidia protozoans) longest word with horizontal line of symmetry, in upper-case letters.

Hamamelidaceae (witch-hazel) - Letters from 1st half of alphabet.

Phaeophyceae (brown algae) - Second-longest word which, in uppercase, uses only Cyrillic letter look-alikes (the place name Chattahoochee is one letter longer). The word oca (tubers of Oxalis tuberosa) not only is composed of Cyrillic letters, but has a biology-related meaning ("wasp") in Russian.

Hoffmannseggella Jones, 1968 (orchid) - Four different doubled letters. The specific epithet hoffmannseggii exists also in the genera Capperia (moth), Cassia (Fabaceae), Guettarda (Rubiaceae), Ichnanthus (bedgrass), Licinus (ground beetle), Myrcia (Myrtaceae), Oulema (leaf beetle), Philodice (Eriocaulaceae), Platyarthrus (isopod), and Porcellio (isopod). Note that four of these give five different doubled letters for the combination.

Leuhea seemannii (Panamanian tree) - 3 doubled letters out of 9 letters.

leucocytozoans (protozoa parasitic on birds) - Typed with right and left hands alternating.

Prorhipidoglossomorpha (branch of molluscs) - 22 letters, no 'e'.

Munnogonium - Pleurogonium - Pleurosignum - Austrosignum - Austrimunna - Munnogonium (paramunnid isopods)

Paramunna - Munnogonium - Pleurogonium - Pleurosignum - Austrosignum - Austronanus - Spiculonana (paramunnid isopods)

Munna - Haplomunna - Haplodendron - Dendromunna - Munna (janiroidean isopods)

auks, skua - one type of bird a reversal of the other.

dividivi (Caesalpina coriaria, a tropical American tree) longest word composed of Roman numeral letters.

puttyroots (the orchid Aplectrum hyemale) and zoosporous -- Ten-letter words consisting entirely of letters from the second half of alphabet.

watercresses - typed only with left hand.

Johnny-jump-up (violet, e.g. Viola tricolor),

pepperroot (Dentaria lacinata), pepperwort (Marsileaceae, a marsh fern), pewterwort (Equisetum), poppywort (Meconopsis), tetterwort (Sanguinaria canadensis), and rupturewort (Achyranthes polygonoides) - typed with only top row of keys. "Poppyworts" also uses letters only from the second half of the alphabet.

alfalfas - typed with only middle row of keys.