In a friend’s sunny Kaimuki cottage filled with vintage furniture, floral designer Tamara Rigney laid out her freshly gathered botanical palette.

It included different shades and textures of green: the pale, smooth leaves of paperbark eucalyptus and dark, feathery ironwood needles. “It pops,” Rigney said of the contrasting hues. “Branches are very on trend right now.”

The Honolulu native was demonstrating how to make holiday bouquets from materials collected outdoors. It’s the theme of her new book, “‘Ohi: How to Gather and Arrange Hawai‘i’s Flora” (Paiko Press, $22), co-authored with photographer Mariko Reed.

Rigney had gathered some of her materials from her own and friends’ yards, farmers markets and the side of the road on her morning drive. Others she obtained from local farms through her businesses, Honolulu botanical boutique Paiko and floral design studio ‘Okika.

“All this stuff is pretty common,” Rigney said. “I tried to choose stuff that’s not exotic, so people can relate.” One easy decoration pictured in “Ohi” consists of a baby palm tree sprouting from its own coconut base.

Gathered materials such as bougainvillea, plumeria, white ginger, philodendron, crotons, ti leaves and ferns predominate in the many different arrangements Reed photographed for the book.

“It’s our big theme: Go to the farmers market and just buy a couple of stems, like torch ginger, heliconia, protea or anthuriums, and fill in the rest with found stuff,” said Reed, who grew up on Oahu and lives in California, working as an architectural photographer.

In keeping with the authors’ sustainable ethos, they like to harvest invasive plants, using strawberry guava and pink bananas, which are “not edible and just explode with seeds,” Rigney said.

The authors advised taking care not to pick native plants in forests and parks; a list can be found at nativeplants.hawaii.edu/plant. Permits are required to gather plant materials on public lands; an application form can be found at dlnr.hawaii.gov/dofaw/permits.

“Get to know your neighbors,” Rigney said with a smile, saying she has asked permission to pick from yards since her Aina Haina childhood when she “lived for May Day, when we decorated Wailupe Elementary School.”

After testing different groupings of flowers, Rigney made several bouquets.

Some were small: two red anthuriums and two uluhe fern curls in a glass bottle; lauae ferns and round clusters of tiny star-shaped red blossoms from ixora, a common shrub, in a vintage pot of etched brass, a metal that “feels very holiday,” Rigney said.

Others were tall and dramatic, such as red Collinsiana (hanging) heliconia with branches of Manila palm seeds, which “are considered yard rubbish,” Reed said, in a ceramic vase by Speedy Jane Studio in the Manoa Potters’ Guild.

All looked simple, uncluttered and spontaneous. “The loose, gathered feel is big now,” Rigney said, noting that as someone who “can’t follow a recipe,” she doesn’t follow any rules in flower design.

The authors agreed their essential goal was to get people to go outside and enjoy gathering and composing their own unique, natural holiday accents for the home.

For more tips and many beautiful photos, see Rigney’s and Reed’s new book, “Ohi: How to Arrange Hawai‘i’s Flora.” They will be demonstrating arrangements in a class at Paiko from 6:30 to 8 p.m. Thursday; for more information, visit paikohawaii.com/workshops-1/2016/12/22/local-flower-arranging-for-the-holidays.