Using Latin binomials and common names of organisms
Biologists often need to use both the
Latin and the common names of organisms. Here is a simple
guide to good practice.
1. At the first mention of an
organism (e.g. baker's yeast), give its full Latin
name (binomial) in italics or underlined: Saccharomyces
cerevisiae or Saccharomyces cerevisiae.
After that, you can write S. cerevisiae, or
just Saccharomyces if it is clear to the
reader that you are talking about only the one
species of Saccharomyces.
2. If you use the common name of an
organism, then you write dog whelk or rosebay
willowherb, not Dog Whelk or Rosebay
Willowherb. These are common names, as opposed to
proper names, so they do not need Capital letters.
3. When you are talking about a
Family, Order or Class (or any other hierarchical
grouping of organisms above the level of genus) you use
a Capital but do not use italics.
For example, the frogs and toads are in the Class
Amphibia, or just in the Amphibia. But when you write
about these organisms in an essay, you can use the
word 'amphibians' (a common name, without a Capital).
Here is a short section with
several examples of correct usage. [I use square
brackets for explanations]
"The amphibians [common
name] are found mainly in moist habitats, whereas
members of the Reptilia [proper name] occur
in drier environments. Both groups are members of the
Chordata [proper name] which encompasses [note
that Chordata is singular] a wide range of
animals, including humans. Chordates [common
name, plural; note that it has a Capital only
because it starts a sentence] are characterised
by having an internal skeleton, in contrast to
arthropods, which have an exoskeleton."
Here is one of the
Wrong: The Arachnida are found across the world.
Correct: Members of the Arachnida are found across
Explanation: The Arachnida is a
taxonomic group- one group
- so you cannot talk about it as a plural.
4. A final point - you must
always "respect" proper names. For
example, the following are WRONG.
The Mucor sporangium is
inflated. [Mucor is a proper noun, so it
cannot be used as an adjective. Instead, write 'The
sporangium of Mucor is inflated.']
Canis lupus's skull is
large. [Write 'The skull of Canis lupus is
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There are only a few abbreviations that
you will need to use.
- e.g. meaning 'for example'
(for information, it comes from the Latin, exempli
- i.e. meaning 'that is'
(from the Latin id est). Note that
'i.e.' specifies particular things, whereas
'e.g.' gives examples.
- etc. meaning 'and so forth'
(from the Latin et cetera) [Some people,
wrongly, write ect.]
- et al. meaning 'and others'
(from the Latin et alia). You would use
this only when citing references.
Normally, you would use i.e. and e.g. in brackets or
within dashes, as in the following examples.
Several ions (e.g. chloride, nitrate) were
found to interfere with the assay.
Several ions - e.g. chloride, nitrate - were found to
interfere with the assay.
The larger of the two bacteria (i.e. Bacillus cereus)
was found to grow faster.
The larger of the two bacteria - i.e. Bacillus cereus
- was found to grow faster.
[Incidentally, you might notice that putting
something in italics - as you might do for the
heading or subheading of an essay - fails to
distinguish a Latin word or name (Bacillus cereus)
from the rest. The solution that many scientific
journals adopt is to put the Latin word in normal
typeface (termed Roman typeface). For example, a
heading could be: The bacterium Bacillus
cereus and other food-poisoning organisms.]
A few points
Word endings: -ise and -ize
Often the choice of -ise or -ise is optional. But, increasingly
we are moving towards -ise as the preferred option.
Thus: optimise, theorise, hypothesise, plagiarise,
There are no simple rules governing the use of hyphens
(un-coordinated, well-written, etc.), so judgment and
common sense are required. Many scientific journals,
especially in the USA, discourage the use of even
well-chosen hyphenated words. But imagine that last
sentence without the hyphen; you would have a string of
descriptive words (even, well, chosen, hyphenated) to
sort out for yourself.
In general, hyphens should be used only to avoid
confusion of meaning. For example:
- a walking-stick certainly is different
from a walking stick, but a reader is
unlikely to be confused if you miss out the
- it is normal to write ninety-first (and
similar) instead of ninety first;
- it makes sense to use hyphens for compound
adjectives (e.g. a gorse-covered hill, a
well-chosen site, a time-limited
- the Edinburgh-Glasgow railway line is
different from the Edinburgh Glasgow line;
- a black-backed jackal is different from
a black backed jackal (which must be
black all over, as well as having a back)
- it is usual to hyphenate when a noun is used as
an adjective (e.g. tooth-decay, mountain-bike);
- the prefix 'non-' is often hyphenated
(e.g. non-usable, non-stick, non-smoker) but 'un-'
is usually non-hyphenated (unusable, unstuck,
- times such as 9 o' clock (9 of the
clock) should not be hyphenated;
- you might be alarmed if you read in your
coursebook the instruction "Tonight you
should look up the rectum" - even if
that is technically correct, it would be sensible
to hyphenate (look-up) the compound verb
(to look up, meaning to consult)!
Advice: Instead of using hyphens,
think about joining the words together if this seems
reasonable. For example, a web site (or web-site)
could equally well be a website. If you
type 'website' in a Windows program (which, incidentally,
is the proper spelling of programme when you are
referring to computers) then the Spelling Tool will tell
you it is wrong. But it will be the norm in 5 years time.
Wake up, Bill Gates!
Some anglicised Latin words:
singular and plural
Many people have problems with the
singular and plural forms of Latin and Greek words - and
In most cases you just have to learn
the terms. But there are a few rules to (partly) help
- There are five common endings to
the singular form: -a (as in
alga), -us (as in fungus), -um
(as in bacterium), -is (as in
hypothesis), -on (Greek, as in
- Each of these has its own plural
form: -ae (as in algae), -i
(as in fungi), -a (as in
bacteria), -es (as in
hypotheses), -a (Greek, as in
- One alga,
(and similarly for corona, papilla).
- One fungus,
(and similarly for pilus, locus).
- One bacterium,
(and similarly for sporangium, cerebellum,
medium, datum - yes, data is the plural form).
- One hypothesis,
(and similarly for thesis, prognosis, diagnosis,
- One mitochondrion, several
mitochondria (similarly for phenomenon,
The following table lists some of the commoner terms.
|datum (seldom used)
||Write "these data",
"the data show"
||Never write "this culture
||A septum, several septa
||We noticed a phenomenon.
|protozoan (or protozoon)
||Leaves have stomata (but, stomates according
|taxon (any taxonomic category)
||None means "not one". So you write
"none is", not "none are".
Spelling - some commonly misspelt words
||Wrong (or, at least, not what
|affect (verb - to influence something)
(see also effect further down this list)
a verb) - when you
affect (verb) something you cause an effect
||currant (a thing you find in a bun)
(this is a participle - something is dependent on
something else; e.g. children are dependent on
(but correct as a
noun - a person who depends on another; e.g.
children are dependants)
(a dry place)
(not a dry place) something you
eat in a pretentious restaurant
(usually a noun, but used as a verb in a very
restricted sense- e.g. to effect (bring about) a
||favor (American spelling)
(e.g. to judge something, or a thing
(verb - the form used in the past tense;
e.g. it led to or he led me)
||lead (the present
tense of the verb; e.g. I lead a
good life) but often wrongly used
in place of led
(noun, e.g. driving licence)
(this is correct as
a verb - to permit or authorise)
(verb - let sleeping dogs lie, to lie on a bed).
It becomes laid or lay
in the past tense (yesterday the dogs lay for
hours; I laid it down)
(what hens do), becomes layed in
the past tense
(to lose something)
||loose (your clothing can be loose)
be (e.g. It may be blue, or
(this means perhaps; it does
not mean may be)
(noun - a doctor's practice)
(verb - a doctor practises, and so does a juggler
if he wants to be good)
(one of those rules you hold dear)
(remember that you can separate
(paper, sold by a stationer)
(because a group is a taxon)
||tumor (American spelling)