Sydney Parkinson; Family: Araceae, Genus/Species: Arum italicum; 1768; Natural History Museum, London, Great Britain

Gerrit Shouten; One Botanical Study; 1820-1830; watercolor; 56.7 x 44.6 cm; Fine Arts Museum of San Francisco

Jan van Kessel; Peapods and Insects; c.1650; oil on copper; 13.7 x 19.1 cm; Fine Arts Museum of San Francisco

Tacuinum Sanitatia Codex 4182 fol. 76r fennel (feniculus); early 14th century; Biblioteca casanatense

Albrecht Dürer; Large Piece of Turf (The Great Turf); 1503; watercolor and tempera on paper, mounted on cardboard; 410 x 315 mm; Graphische Sammlung Albertina

Hannah Cohoon; Gift Drawing: The Tree of Light or Blazing Tree; 1845; ink, pencil, and gouache on paper; American Folk Art Museum

Artist unidentified; Ephrata Cloister Tunebook; c.1745; watercolor and ink on paper, with cloth and leather binding; American Folk Art Musuem

Mary Vaux Walcott; Untitled–Flower Study; 1940; watercolor on paper; 25.5 x 17.9 cm; Smithsonian American Art Museum

Winold Reiss; Flower Design for Wallpaper or Textile; 20th century; gouache on heavyweight board; The Minneapolis Institute of Arts

Adolf Wölfli; Holy St. Adolf Tower; 1919; pencil and colored pencil on paper; American Folk Art Museum

Joseph Stella; Flower Study; c.1919; silverpoint and crayon on prepared paper; 32.8 x 16.5 cm; Smithsonian American Art Museum

Mary Vaux Walcott; Leather Flower (Clematis hirsutissima); c.1930; watercolor on paper; 25.5 x 17.7 cm; Smithsonian American Art Museum

Mary Vaux Walcott; Untitled–Flower Study; c.1900-30; watercolor on paper; 25.5 x 17.7 cm; Smithsonian American Art Museum

Georgia O’Keeffe; Banana Flower No. II; 1934; charcoal on paper; Georgia O’Keeffe Museum

Charles Burchfield; Dream of a Fantasy Flower; 1960-66; watercolor with wiping and scraping; Terra Foundation for American Art

George Elbert Burr; Untitled (Cardinal Flower, Lobelia cardinalis); 1889; pen and ink on paper; 36.5 x 27.5 cm; Smithsonian American Art Museum

Mary Vaux Walcott; Untitled–Flower Study; c.1883-1900; watercolor on paper; 31.6 x 23.9 cm; Smithsonian American Art Museum

Morris Graves; Winter Flower; 1954; Pastel and gouache on toned paper; 20.32 x 27.94 cm; The Phillips Collection, Washington DC

Mary Vaux Walcott; Untitled–Flower Study; c.1876-8; watercolor on paper; 22 x 16.8 cm; Smithsonian Art Museum

Donald Baechler; Yellow Flower #2; 1995; gesso, gouache, pencil, ink and collage on paper

Georgia O’Keeffe; Untitled (Flower); 1959-60; graphite on paper; Georgia O’Keeffe Museum

Georgia O’Keeffe; Untitled (Flower); c.1930-6; graphite on paper; Georgia O’Keeffe Museum

Georgia O’Keeffe; Untitled (White Flower on Red Earth); 1943; graphite on paper; Georgia O’Keeffe Museum

Jan van Huysum; Flower study; early 18th century; watercolor; 181 x 272 mm; British Museum

Jan van Huysum; Flower study; early 18th century; watercolor over traces of graphite on paper; 235 x 171 mm; British Museum

Jan van Huysum; Flower study; early 18th century; watercolor on paper; 121 x 130 mm; British Museum

Jan van Huysum; Flower study; early 18th century; watercolor on paper; 192 x 130 mm; British Museum

Jan van Huysum; Flower study; early 18th century; watercolor over traces of graphite; 283 x 186 mm; British Museum

Jan van Huysum; Flower study; early 18th century; watercolor on paper; 204 x 154 mm; British Museum

Vincenzo Leonardi; Lemon, Citrus limon (L.) Burm. f.: flowering twig; watercolor and bodycolor over black chalk; 276 x 189 mm

Jan van Huysum; Flower study; early 18th century; watercolor on paper; 91 x 113 mm; British Museum

Odilon Redon; Strange Flower: Little Sister of the Poor; 1880; charcoal; 40.4 x 33.2 cm

Thomas Watling; Plant, a Banksia; c.1972-97; watercolor; 31.8 x 23 cm

Port Jackson Painter; Un-named flowering plant; c.1788-98; watercolor; 31.8 x 19.8 cm; The Natural History Museum, London

Port Jackson Painter; Un-named plant (possibly a species of Hyacinth orchid Dipodium); c.1788-97; watercolor and body color; 30.4 x 17.1 cm; The Natural History Museum, London

Port Jackson Painter; Un-named flowering tree or shrub (possibly of the Fabaceae family); c.1788-97; watercolor and ink; 27.5 x 17.4 cm; Natural History of Museum

Port Jackson Painter; Un-named plant (a species of Acacia); c.1788-98; watercolor; 31.9 x 20.1 cm; The Natural History Museum, London

Artist unknown; Hyacinth; watercolor; 38.3 x 25.4 cm; The Natural History Museum, London

Port Jackson Painter; Banksia spinalosa, native name “Wallangre”; c.1788-97; watercolor; 30.3 x 16.4 cm; The Natural History Museum, London

Port Jackson Painter; Un-named flowering Plant (a species of Banksia); c.1788-97; 32.9 x 21.5 cm; The Natural History Museum, London

Thomas Watling; Plant, “a Banksia”; c.1972-97; watercolor and glazing in darker areas; 35 x 23.5 cm; The Natural History Museum, London

Port Jackson Painter; Un-named flowering plant (possibly the Tongue orchid Dendrobium linguiforme); c.1788-97; watercolor; 22.2 x 19.7 cm; The Natural History Museum

John Langley Howard; Rock and Grass; 1986; watercolor

Charles Chase Emerson; Landscape; 1901; graphite on paper; 24.8 x 17.9 cm; Sterling and Francine Clark Art Institute. Dept. of Prints, Drawings and Photographs

Sydney Parkinson; Family: Droseraceae, Genus/Species: Drosera peltata; 1770; Natural History Museum, London

Port Jackson Painter; Un-named flowering tree (possibly Acacia); c.1788-97; watercolor, ink, some glazing; 37 x 23 cm; The Natural History Museum, London

Port Jackson Painter; Fruiting tree, “Stipalix”; c.1788-97; watercolor and ink; 29.9 x 20.2 cm; The Natural History Museum, London

Jacob van Ruisdael; Dune Landscape with Oak Tree; 1650-5; black chalk, brush and gray wash, gouache; 21 x 19.1 cm; The Metropolitan Museum of Art

Antoine Louis Barye; Vultures on a Tree; XIX century; watercolor; 27.1 x 38.4 cm; The Metropolitan Museum of Art

Egon Schiele; Horse Chestnut Tree, Lake Constance; 1912; watercolor and pencil; 45.8 x 29.5 cm

Jacob Ligozzi; The Beech Tree of the Madonna at La Verna; 1547-1627; pen and brown ink, brush and brown wash with traces of gray wash, over black chalk; 40.2 x 25.7 cm; The Metropolitan Museum of Art

Jean Baptiste Camille Corot; Bent Tree by the Water; charcoal, with stumping and erasing; 454 x 552 cm; The Art Institute of Chicago

Roy Lichtenstein; Untitled study (Tree); 1991; graphite on paper; 17.8 x 12.7 cm

Adolf von Menzel; Study of a Tree; c.1885-90; graphite on wove paper; 18.3 x 11.5 cm; Fine Arts Museum of San Francisco

John Varley; Landscape with Tree and Cottage; 18th-19th century; drawing; 24.1 x 20.6 cm; Fine Arts Museum of San Francisco

George Henry Boughton; Study of a Tree; c.19th century; graphite; 24.2 x 17 cm; Fine Arts Museum of San Francisco

David Johnson; Pine Tree, Conway, New Hampshire; c.1851; graphite with pen and brown ink; 36.2 x 25.4 cm; The Cleveland Museum of Art

David Johnson; Chestnut and Pine; 1869; graphite; 30.5 x 46.9 cm; The Cleveland Museum of Art

Charles Livingston Bull; Weasel peering into tree root; c.1890-1932; charcoal; Library of Congress, Prints and Photographs Division, Washington DC

Renée Magritte; Le 16 Septembre; c.1955; gouache

Edward Henry Potthast; Study of a Tree; graphite and blue, green, and brown colored pencil on paper; The Minneapolis Institute of Arts

Jean-Baptiste Camille Corot; Landscape, with large tree on left, two figures at right, one holding long pole; 1860s; brush and brown wash on beige wove paper; 7 x 9.5 cm; Museum of Fine Arts, Boston

Théodore Rousseau; Tree Study; 1825; graphite and white chalk on lavender wove paper; The Minneapolis Institute of Arts

Daniel Carter Beard; A tree is known by its fruits; c.1889; Library of Congress Prints and Photographs Division, Washington DC

Thomas Fogarty; For friendly confidences give me an apple tree in an old green meadow; c.1917; crayon; Library of Congress Prints and Photographs Division, Washington DC

THéodore Rousseau; Tree Study; 1825; graphite on white wove paper; The Minneapolis Institute of Arts

Georgia O’Keeffe; Untitled (Banyan Tree); 1934; graphite on paper; Georgia O’Keeffe Museum

Georgia O’Keeffe; Dead Cedar Tree; 1937; graphite on paper; Georgia O’Keeffe Museum

Jean-Francois Millet; Figure Seated Under a Tree; 1852-53; conté crayon on paper; The Phillips Collection, Washington DC

Jean Pillement; Sketch of a tree; 18th century; Crayon; Museum of Fine Arts, Boston

Georgie O’Keeffe; Old Tree; 1918; watercolor on paper; Georgia O’Keeffe Museum

Georgia O’Keeffe; Untitled (tree); 1940s/1950s; graphite on paper; Georgia O’Keeffe Museum