I’d be curious what the statistics are on how often those signs are actually right. Definitely seen totally wrong ones, not sure if its because something else invaded after the sign was placed or if they were wrong to start with.
I generally assume the variety/cultivar is correct if I am confident the species is correct though.
As a professional in that field, I’d say wrong signage is usually because the plant matching the sign died or moved, but the sign was not removed or moved. The frequency of that varies wildly from garden to garden, depending on their availability of staff and money for sign upkeep.
On iNat occasionally it’s photographer error, like the area has several plants close together and the observer guessed incorrectly which plant went with the sign, even though the right plant was present too.
Of course it’s possible that the sign was always wrong; that is to say, the plant was incorrectly identified by the person who then made the sign. Usually when that happens it’s a plant that’s widely available in the hort trade under the wrong name, and those are often blogged about somewhere (examples: https://www.smgrowers.com/info/kalanchoeluciae.asp or https://en.m.wikipedia.org/wiki/Cochliasanthus) Or less often it’s something close but not ridiculously unrelated, such as correct genus but incorrect species.
We took a work team building trip to a TPWD State Park in November 2019, where we cleared cedar for fire breaks & put informational signs about the non-planted flora at various points along the trails (Loblolly Pines, American Beautyberry, Texas Bluebonnets, Yaupon Holly, etc). There were no bluebonnets out, because it was November, but the park interpreter was pretty confident the field would have bluebonnets in the spring, while admitting the sign might not be accurate by then.
One in this high school batch ive been seeing (I’ve lost count of how many pages - 30 obs each - I’ve sorted through now) is def wrong, i think maybe it was you who corrected it? And it was uploaded about 20 times by different people. Some of the others I’m not sure are correct either.
Some from the botanical gardens down by Auburn I think are wrong as well in those images that I see, because it will call for a fern or something, and theres certainly no fern in the photo.
I often see people photographing the wrong plant near a sign and assuming it’s the one the sign refers to. But the one that really drives me up the wall is when people put in a wrong ID for something when there’s literally a sign with the correct name clearly visible in their own photograph!
Sometimes the signage is just plain wrong though - a museum near me has a big sign talking about Blue Elder, and how the native american peoples used the berries for food, etc - except the thing they actually planted was Red Elder. Which is poisonous. I let them know, but I doubt it’s ever been corrected.
Could be, one I was thinking of recently was a sign that said ‘garlic chives’ in front of what was obviously just regular ‘chives’ (or vice versa, it included the scientific name so wasn’t just a common names thing). But most of them appear to be as @arboretum_amy suggested cases where whatever was originally there died and now something totally unrelated is present, like some nettles labeled as an aster or whatever.
Not from gardens, but from herbaria:
Widespread mistaken identity in tropical plant collections https://doi.org/10.1016/j.cub.2015.10.002
« Our data demonstrate that, while the world’s collections have more than doubled since 1970, more than 50% of tropical specimens, on average, are likely to be incorrectly named. This ﬁnding has serious implications for the uncritical use of specimen data from natural history collection. »
More times than I would like to count, I have seen a mismatch between the map coordinates of a specimen and the locality described on the label. Sometimes this can be a large enough error to make a difference in the range map.