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What does 'Agg.' mean?

When ‘Agg.’ is added to observations, what does this mean? I have tried researching this but to no avail.

It seems to be used when we can’t refer to a single species for some reason. Agg. stands for something ‘in the aggregate sense’.
Someone else will explain it more fully, I’m sure, as I don’t really understand it myself.

Thankyou for your reply Jane. Does this mean, for instance, that if I ID a ladybird as just ‘ladybird’ rather than the more specific ‘Seven spot ladybird’, I should add Agg. after the ‘ladybird’.
Sorry, I am not the brightest bulb on the Christmas tree.

Agg. and analogous constructions are not normally used with vernacular names, though you might find someone referring to dandelion agg., but in the case of a ladybird it would be ladybird sp. or using biological nomenclature Coccinellidae sp., meaning an unidentified/unknown species of the ladybird family.

An aggregate is a

  1. A group of closely related forms where it is unclear how many species there are, e.g. Symphytum officinale agg., which is treated in the British floras as a single species, but which arguably is a polyploid complex including 3 species and at least 2 hybrids.
  2. A group of microspecies, such as the the Taraxacum (officinale) agg., the Rubus fruticosus agg. and the Hieracium agg.
  3. A hybrid swarm with indistinct boundaries between the species. (The obvious example here is Narcissus agg., where many of the cultivated varieties are hybrids with complex parentage; to add to the confusion Narcissus contains several aggregates of the first type.)
  4. A group of species which are only separatable by experts (e.g. Euphrasia agg.)
  5. A group of species which are only separatable at certain times of the year (e.g. Galeopsis tetrahit agg., where you need flowers to distinguish Galeopsis tetrahit from Galeopsis bifida)
  6. A group of species which have historically been confused, e.g. the Spiraea salicifolia agg., where British botanists didn’t realise for some time that more than one taxon had become naturalised.

In some cases s.l. (sensu lato) is an alternative to agg. Returning to Symphytum officinale, Symphytum officinale agg. implies that you think there are multiple species, while Symphytum officinale s.l. takes a more agnostic view.

To generalise an aggregate is a group of morphologically difficult to distinguish taxa. Aggregate is not a formal taxonomic rank, so there is no official definition of what is and isn’t an aggregate, and usage does vary. You can even get aggregates included within aggregates. At one point I stretched the concept to use Salix cinerea agg. to cover the sallow species and hybrids, but I’ve since found that there is an infrageneric taxon covering that concept - Salix sect. Cinerella. Salix cinerea agg. could also be used to cover Salix cinerea and Salix oleifolia.


Thank you so much Lavateraguy. I am very grateful for the detailed information you have sent me. I will read it over until it all sinks in (I hope).

I expected it to be complicated, lavateraguy and say thanks for the examples in your detailed explanation.

Perhaps I could attempt a simpler explanation (writing as a complete amateur). The term is used quite frequently with moths, both with scientific and vernacular names. A good example is ‘common rustic agg’. This is a way of recording moths which are certainly one of the three Mesapamea species, which are all variable and can only reliably be separated by genital dissection. Rather than write ‘either common rustic, lesser common rustic or Remm’s rustic’ it is easier to write ‘common rustic agg’. There is, of course, a scientific designation - M secalis agg. There are other examples among moths. Some people will give an exact species but they should only do so based on a close and ideally long-term study of the moths that occur in their area. If, over the years, it is discovered that all of the (say) common rustics have a feature that the other two species lack, it becomes reasonable to use that feature as an ID tool. But it doesn’t mean that it applies in other parts of the country.
I think I’ve managed to make it sound more complicated than it actually is!!
If you look at Common Rustic agg. | NatureSpot you can see this particular agg illustrated… and see why it’s an ‘agg’.


Thank you Kenneth. I appreciate your reply. I am slowly but surely now understanding ‘Agg.’ much better now.

So perhaps (anyone?) it is now worth covering “” to complete the topic.
Well maybe not Complete as there may be more comments on agg. & s.l.

There are 3 main competing current concepts of Plantae - Plantae sensu strictu is Embrophyta (land plants), Plantae sensu lato is Viridiplantae (land plants and green algae), and Plantae sensu latissimo is Archaeplastida (land plants, green algae, red algae, and glaucophytes).
S.s. is basically the other side of the coin to s.l. For the comfreys mentioned above Symphytum officinale s.s. is the lumpers’ Symphytum officinale subsp. officinale.
There are other terms, such as sensu auct. (sensu auctorum), which means in the sense used by various authors (but not the botanist who originally published the name), which is typically used when a name has been misapplied.
WikiPedia has an article on the topic - Sensu - Wikipedia

Thank you. Good to be reminded in wikipedia that Sensu is the ablative case of the noun sensus”. I haven’t seriously considered the Ablative case in a good many years.

I need a sensu capuccino to make sense of the above!

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