Hands up everyone unaware there is such a genre as American Impression-ism.

That is very much the point of an astonishing show at the National Galleries in Edinburgh of 70 paintings by well-known names such as Whistler, Singer Sargent, Mary Cassatt, and the lesser-known William Merritt Chase, Childe Hassam, Edmund C Tarbell and John Henry Twachtman. In a bid to spread the word about the significance - indeed, the very existence - of American painters at the start of the trans-national movement, the Foundation for American Art Terra has heavily invested in this touring exhibition. It kicked off at Giverny, where it all began, and after Edinburgh goes on to Madrid.

Impressionism didn't take hold in the US as straightforwardly as it did in France and the UK. Some American painters worked in France, others learned of the movement through the paintings they saw in Paris, and others on their home turf of Boston and New York. They appropriated some aspects of it and invented others, adapting for an American audience.

Even if the artists concerned may not be Impressionists in the usual meaning of the word, France permanently changed the face of American art. One critic notably described it as "looking at America though French spectacles".

Although no Americans exhibited at the very first Impressionist exhibition in Paris in 1874, it was a woman, Mary Cassatt, who was the first American to exhibit a painting at the Paris Salon that year; by 1877 she'd been invited to exhibit with the Impressionists in future shows.

Frances Fowle, curator of the Edinburgh exhibition, admires her "unsurpassed ability to infuse her compositions with an engaging naturalism". Theodore Robinson was another of the select few invited into Monet's circle at Giverny.

But according to Fowle, the extent to which Monet influenced the artists who worked at Giverny is questionable. They were arguably more influenced by naturalists such as Bastien-Lepage and by other artists on the edge of Impressionism. On the other hand, there is much overlap: in Robinson's series of haystacks there's a definite echo of Monet's iconic 1891 Haystacks.

It had been so successful that in the very same year both Robinson painted Afternoon Shadows, a study in haystacks; and Breck produced a series of 12 oil studies of haystacks, Studies of an Autumn Day. Monet subsequently banished Breck from Giverny.

"Painting subjects close to Monet's had an ulterior motive, since the value of his pictures was steadily rising," says Fowle. "This must have been annoying for Monet, for the idea of repetition was his."

So is American Impressionism simply derivative?

As Impressionism spread to America as it did to other parts of Europe, people were reluctant to regard it as better than French art. But then again there was a natural flux between all Impressionist painters in America, Europe, and the UK who visited France.

The question as to whether the American Impressionists could be described as a distinct group - like, say, the Glasgow Boys - defies a straight answer. There hasn't been an exhibition devoted to them in this country before; the 2006 Americans in Paris exhibition at the National Gallery in London focused on the individual artists and drew attention to the fact that they had never before been hung together.

But founding members of Ten American Painters [The Ten] group, formed in 1897 by defectors from the Society of American Artists, included Hassam, Twachtman and Tarbell, who first exhibited together in New York in 1898; they were later joined by William Merritt Chase.

The American Impressionists were arguably more diverse, the figurative painters among them perhaps the more technically American.

Tarbell's Three Sisters features a chair with a distinct American Colonial look; there's a "chocolate box, wholesome feel" that lacks any shock factor. Dessart's Peasant Woman and Haystacks, painted in Giverny in 1892 is a more idealistic version of Bastien-Lepage's The Return from the Field painted 14 years earlier. Painting ordinary scenes en plein air was very much in the sprit of Impressionism.

Hassam's development is evident in the gradual switch from a darker palette and subject matter of, say, Une Averse - Rue Bonaparte 1887 to brighter, softer, more fragmented brushstrokes and unusual viewpoints in Poppies on the Isle of Shoals of 1890, reflecting Monet's influence.

Similarly, New Yorker Dennis Miller Bunker switched between moody figurative work and colourful American landscapes such as Roadside Cottage and The Pool, Medfield; though cut short by his death at age 29, his artistic journey is of interest to Fowle who says he was striving to fully embrace Impressionism.

Twachtman's mesmerising Winter Landscape takes him beyond Impressionism; and Thomas Dewing's meditative, dreamlike use of colour makes him unique in the group.

"The Americans were united by Impressionism but often painted very different subjects and styles," Fowles concludes.

One notable aspect of this impressive body of work is the absence of the cafes and bars so frequently depicted in French Impressionism. "The American Impressionists didn't really engage with the Bohemian lifestyle, because they were conscious of their American market," explains Fowle.

Demonstrating that for many American artists, Impressionism was not a final destination, but a process.

American Impressionism - A New Vision, 1880-1900, opens at the National Galleries of Scotland on Saturday July 19, 2014, and runs until Sunday October 19, 2014. www.nationalgalleries.org