Flowers, those sure signs of spring, are sprouting up all over New York Fashion Week runways.

Marc Jacobs tucked giant flowers into models’ hair. Flowers also bloomed at Donna Karan in muted neutrals, and they peeked through the runways of Tracy Reese and Jenny Packham.

The optimistic symbol goes hand-in-hand with the airy lightness that has prevailed so far at the spring 2011 previews that run through tomorrow. These florals were more earthy, soft and natural than fashion insiders have seen in recent seasons. They looked like real flowers — not perfect, but alive.

Donna Karan

Donna Karan presented a runway almost completely in shades of sand to capture the essence of "raw romance."

From billowy, featherweight dresses to tailored jackets in a stiff metallic twill, the common theme of each piece — other than the palette — was a celebration of a strong, confident muse. This woman really could be anyone: young or old, petite or glamazon, working mom or globe-trotter.

When Karan hits it right with her signature line, it’s all about speaking to the potential of the women who wear it. She has hit her stride in recent seasons and she extended that streak into next spring, although surely the retailers in the audience wished to see a little more color.

But it was the use of skin tones, from dark to light, that was so effective in conveying a sense of the natural. The sheer trend that’s been seen on the runways got its due in slip dresses and a finale gown made of pale gold tulle that disappeared on the model save a pattern of glittery beading.

Tracy Reese

Tracy Reese likes her catwalk to be a happy place and she consistently turns out clothes that suit that mood.

For the spring collection that previewed Monday at Mercedes-Benz Fashion Week, she used words like "mellow" and "groovy" to describe the prevailing look. (The red flared pants make so much more sense now.)

A black halter maxi dress, a waves-and-orchid print peasant blouse and the poncho worn over a tie-neck blouse and Bermudas all channeled the relaxed style of a woman unconcerned about her BlackBerry or iPhone — if she even owns one or knows what it is.

But the inspiration here wasn’t sheltered or old-fashioned, either: While Reese’s muse fully embraces the season’s relaxed silhouettes — right down to the floppy hats — she also wears leather bra tops and a perforated halter dress.

Marc Jacobs

A lot of designers have disco danced around a 1970s muse with those billowy shapes, scarf-tied tops, gold lame and long, flared trousers. But Marc Jacobs, probably the most influential fashion force in New York, is the only one who fully asked her to dance.

He had those looks and more, including jumpsuits, hot pants, culottes and those tight striped knits popular when many in the audience were probably in grade school.

The retro vibe was amplified by frizzed-out hair, metallic sparkle eye shadow, floppy hats and giant, oversized flowers in the hair, around the neck or on thick, cinching belts.

There was a bit of a tropical feel to the collection — it is for spring, after all — with one top covered in palm-tree beading. The colors included purple, orange and hot pink, all of which are showing staying power through this round of style previews. For good, glitzy measure, there were silver and gold sequins, even on some platform sandals.