I'm looking for a plant that will grow fast enough and be clippable in one season as an annual, or a perennial that is hardy to USDA Zone 4, to make a low hedge (not boxwood). I saw this low clipped hedge at a public gardens near the St Lawrence in Ontario, it reminds me somewhat of savory but if it had any flowers to help ID it they'd been clipped off. Does anyone have any idea from the leaf arrangement what it might be?

The plant looks like an Asteraceae to me. If you zoom in on the photo, you can see that there are a number of small yellow buds or flowers in the leaf axils along the stems. The leaves are rather hairy which seems unlike savory, Satureja.
The leaf arrangement suggests Artemisia dranunculus to me... could be wrong:
http://luirig.altervista.org/s...

Do you have any other close photos?

I wondered about A. dranunculus too. I crushed a leaf but it was not aromatic. I don't remember if tarragon is aromatic when crushed, though, it's a long time since I've grown it. I tried to get closer-up pictures but the camera insisted on focusing on the background for the sprig shot. The architecture might help, although very out of focus. We thought we could see some bluish filaments on some stems that might have been flowers or the remains thereof, and I'm uploading an attempt at photographing that also, but it doesn't come out clearly. Thanks!

Tarragon is normally anise-scented but the leaf habit and other things sure look like it. Is it somewhere nearby that you could get more clear close-ups showing the old flowers/seed heads/whatever they are? It can help to put your hand behind the stems - it gives the camera a large object to focus on in the same plane as the stems.

There's three so called Tarragons, French, Russian and Mexican. I have no experience with the latter, but I did grow Russian Tarragon from seed years ago but it doesn't have the anise flavour of the 'French' variety. The following link suggests it does, the only scent it had from rubbing leaves as I recall was a slight bitter smell. I bought a pot of the French variety, it was as expected.

http://aggie-horticulture.tamu...

Tagetes lucida (Mexican) is used for landscapes.

http://www.floridata.com/ref/t...

Artemisia dracunculus (French) was from my experience a rather lax plant which wasn't long lived, I kept it in a pot in a cold greenhouse.

http://www.missouribotanicalga...

Russian tarragon (A. dracunculoides L.) can be grown from seed but is much weaker in flavor when compared to the French variety.[3] However, Russian tarragon is a far more hardy and vigorous plant, spreading at the roots and growing over a meter tall

http://en.wikipedia.org/wiki/T...

Yes, it's clearly not Tagetes lucida, but the lack of anise scent may be explained by Artemisia dranunculoides (which I should have included with A. dranunculus - wasn't actually meaning to attempt a distinction between the two).

I took A. dracunculus to mean either French or Russian, since some references seem to give dracunculoides as a synonym. Trying to sort that out gets complicated and it doesn't really matter to me which it is, unless there's a difference for this use as opposed to cooking. I'm guessing if it's tarragon it's Russian given the use to which it is being put, and I think it has paler foliage than the French?

The garden is about an hour and a half away so I'm not sure if we'll be going again before the flower season ends. If it's a perennial it'll still be there though if they're doing the same design next year but I have another idea - there's a herb garden not far from here so maybe I'll head out there at the weekend and check out their tarragon and see if it looks the same. Thanks!

Artemisia dracunculus is an accepted name .

http://www.theplantlist.org/tp...

Artemisia dracunculoides is a synonym of Artemisia dracunculus ...

http://www.theplantlist.org/tp...

But they are different, the French variety can't be grown from seed as it doesn't make any, suggesting it's a sterile hybrid perhaps initially occurring naturally. I found a pdf which tells more, it has a long history!

http://jhawkins54.typepad.com/...

Artemisia dracunculus var. sativa is the name given for French Tarragon but it's not included in the Plant List.

http://www.theplantlist.org/tp...

As found on mobot, Artemisia dracunculus 'Sativa' is given as a cultivar name.

http://www.missouribotanicalga...

Thanks, sorry my comment about taking A. dracunculus to be either Russian or French was in reference to my having originally interpreted the tentative ID to mean it could be either since the accepted name is the same for both until one adds either the varietas or cultivar name for the French. For the purposes of a hedge, narrowing it down to being either would suffice, at least to start with. I've grown "French" tarragon before for cooking and remember having to be careful which tarragon to get and to not grow it from seed, but it is so long ago now that I couldn't remember how closely it matched the plant in the picture. If it's either of the Artemisia tarragons it's an interesting use for the plant and one that I haven't come across before. Trying to find something to make a low "parterre" type clipped hedge like that in USDA Zone 4 isn't easy!

Not tarragon according to our local herb specialist. I looked around their collection and the nearest were hyssop and summer savory. Neither was quite right but close enough to get me thinking about savory again. Did a bit of Googling and came up with Missouri Botanical Garden saying that winter savory (Satureja montana) makes a "Surprisingly good edging plant which may be clipped for a formal effect." I then found a few other references to its being a good clipped edging/hedging plant for use in knot gardens. Anyway, I've emailed the public gardens where I saw the mystery plant so hopefully they will reply with a positive ID.

I did compare to Satureja montana and Satureja hortensis, winter and summer savory, respectively. I thought what I could make out of the flower buds/flowers/seed pods/whatever they are looked odd, but it could all be.
Satureja montana ssp. illyrica is in full bloom here through August and September, so it's surprising not to see obvious flowers in your photos? Haven't grown summer savory so I have no familiarity with that one.

sooby,
This may sound like cheating, but have you contacted the public garden where you saw these plants to ask them for the identity of this plant? Your call may get transferred to several different people, but I think you could obtain the answer by doing this.

Other than that I am thinking that rather than drive all the way over there to take new photos, can you contact a friend in that area who may take the photos for you? Sometimes you can contact a garden club and they may help you...heck, they may even know the name of the plant.

Lori, there probably were flowers but it had been clipped into the formal shape so any open ones had gone. There were some bluish looking "threads" where one might have expected past flowers and I wonder if those were the remains of spent blooms, corolla detached. I'd tried to photograph those but they didn't come out clearly.

Greene, thanks yes, I emailed the gardens yesterday (actually a historical village) so I hope I get an answer.

I heard back from the gardens this morning, apparently it is Kochia scoparia. I'd wondered about kochia but the leaves didn't look as long as one often sees, however looking again it does match some of the pictures of K. scoparia on Google images. Thanks everyone.