4.24 Biological terms

Capitalize the scientific name of a phylum, order, class, family or genus, but not common names or the epithets referring to a species or subspecies, even if they are derived from proper names:

• the phylum Arthropoda
• the order Rosales
• the genus Sporotrichum
• the species Sporotrichum schenkii (second word denotes species)
• The jaguar and the lion are members of the family Felidae.

See 6.11 Mathematical, statistical and scientific material for rules governing the italicization of biological classifications.

Capitalize proper nouns modifying a common name, except where usage has established the lower case:

• Grayson lily
• Cupid’s-delight
• Queen Anne’s lace
• Judas tree
• Canada goose
• Dutch elm

but

• malpeque oyster
• timothy grass

4.25 Chemical, medical and pharmacological terms

In text, do not capitalize the names of chemical elements and compounds:

• krypton
• sodium bicarbonate
• hydrogen peroxide

The capitalization of chemical symbols should follow standard practice:

• H₂O
• NaHCO₃

Do not capitalize the names of conditions, syndromes and the like, but capitalize a personal name that forms part of such a term:

• diabetes insipidus
• Down syndrome
• Huntington’s chorea

Capitalize the names of infectious organisms but not the names of conditions based upon such names:

• People attacked by Salmonella are likely to suffer from salmonellosis.

Do not capitalize the generic names of drugs:

• phenobarbital
• sulfasalazine

© Public Services and Procurement Canada, 2026
TERMIUM Plus^®, the Government of Canada's terminology and linguistic data bank
Writing tools – The Canadian Style
A product of the Translation Bureau