Some examples from Wikipedia:

The hydrangea is a genus...

The Heliantheae (sometimes called the sunflower tribe) are the third-largest tribe in the sunflower family (Asteraceae).

The family Asteraceae (/ˌæstəˈreɪsiː/),[citation needed] alternatively Compositae (/kəmˈpɒzɪtiː/),[citation needed] consists of over 32,000 known species of flowering plants in over 1,900 genera within the order Asterales. Commonly referred to as the aster, daisy, composite, or sunflower family, Compositae were first described in the year 1740.

Asterales /æstəˈreɪliːz/ is an order of dicotyledonous flowering plants that includes the large family Asteraceae (or Compositae) known for composite flowers made of florets, and ten families related to the Asteraceae.

What is the regularity or rule for using singular or plural verbs for them, and why?

  • 1
    Please give links to your quotes. The first, which I find a strained usage, seems to be from 'The Practical Planter', whose editorial control is hard to predict. Commented Mar 10, 2022 at 17:50
  • Every page title is what plant name I quoted respectively, you can search it in Wikipedia Commented Mar 11, 2022 at 5:13
  • 1
    As with other questions about collective nouns, it depends on whether you logically view it as a single thing or as a group of things.
    – Stuart F
    Commented Apr 9, 2022 at 19:16
  • I can't find 'The hydrangea is a genus...' anywhere in Wikipedia. I can only find it in a publication whose editorial policies I can't evaluate. Commented May 10, 2022 at 11:09
  • @BeauGarçonIdolLucianus, please add the links or ask for help. The goal is to reduce duplicated work by reviewers.
    – jimm101
    Commented May 18, 2022 at 15:09

2 Answers 2


In terms of morphology (word formation), the standard pattern in binomial nomenclature is that genus names have the form of Latin singular nouns/adjectives, while higher ranks have the form of Latin plural nouns/adjectives.

The official recommendations of the International Code of Nomenclature for algae, fungi, and plants are in line with treating these names as singular and plural respectively (See Giacomo Catenazzi's answer to Are there cases when genus name is equal to the name of a higher taxon? on Biology SE).

Therefore, it would be preferred on the basis of these standards to write "Asterales are an order" or "The Asterales are an order". In fact, "The Asterales are an order..." sounds better to me than "Asterales is an order...". It is perfectly grammatical to use a plural noun as the subject in a sentence with a singular noun as the predicate, and the standard rule in English is for the verb to agree in number with the subject and not the predicate in such cases. However, the influence of the singular predicate noun might incline some writers to put the verb in the singular in sentences like this.

Actual usage in English varies somewhat according to the variability in treatment of "collective nouns" mentioned in the comments.


As you probably already know, there is a binomial (two name) Latin convention used for plants. Some of these names become abbreviated in common parlance to refer to all varieties within a particular genus. Given the origin of those names, it follows that their plurals should follow Latin rules.

I found this useful site which provides examples of how Latin plural rules are applied. This might help you to determine whether you are looking at a plural or singular noun.

  • Do English-speaking biology scholars know these rules, or were they taught this kind of knowledge in school? Commented Mar 11, 2022 at 5:03
  • But do most people who have never studied Latin mess up the verbs when talking about biological classification? Commented Mar 11, 2022 at 5:08
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    OP is asking about whether to use 'Asterales is' or 'Asterales are' (and I suppose about article usage), not how to pluralise say Quercus, Leachus. Commented Apr 9, 2022 at 18:39
  • Biological Latin (and Greek) is one of the things you have to learn if you want to be a biologist, like the periodic table and statistics. It's not part of English language or usage. Commented May 10, 2022 at 13:28

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