DRAW ME A LEAF
Drawing a leaf offers a simple yet powerful way to talk about principles that apply equally to graphic design, sculpture, architecture, or urban planning. To draw a leaf, you have to identify all the parts: stem, veins, top and bottom surfaces, and edges. The parts vary in quality from species to species. I’m unlikely to mistake a nettle leaf for a fern. Neither, however, would I confuse either of them for bark, branches, or roots. As leaves, they share essential properties.
Leaves exist whole; they have centers and edges. But centers and edges alone don’t make them leaves. What we recognize as “leaf” – rather than a box, a cow, or a brick – requires a visual language. That language is made up of principles common to all leaves, but which also allow each particular leaf to tell its own story, whether it’s high up in a maple tree, or hugging the ground in a fern. Those principles are expressed, visually, by the parts that connect to make the whole. They work, incrementally, by steps. Visually, this translates as scale, but a scale is not just a way to measure pounds and ounces. In Latin, scala means “step,” so a scale provides the means to do gradually what you can’t possibly do all at once; they make a path from here to there. Only Superman can leap tall buildings in a single bound. The rest of us will just have to use the stairs.
In the same way, a leaf cannot turn sunlight into sugar and transport those sugars to the rest of the tree all at once. Rather, the central stem that serves as the main artery between leaf and branch also divides the leaf (typically into 2, 3, or 5 parts, which, as you may have noticed, makes part of a Fibonacci series – and helps explain why it’s so rare to find a four-leafed clover – more about that later). Looking closer at each of those individual parts, we see them further divided by branching veins. Each vein further divides the leaf into pieces of more or less regular shape, and each piece is composed of cells, too small to see, where the chlorophyll actually does its work. Each step serves a different biological function – transport vs manufacture – and also divides the leaf into recognizable parts that we can draw.
Scale functions by creating patterns: shapes and lines that divide, separate, and organize the whole in ways that are both regular and rhythmic. Notice how the fern leaf is put together: one basic shape repeats, growing from small to large and back again. The veins in the nettle leaf also repeatedly divide the whole into similarly shaped segments. So nature uses alternating repetition of individual units to make large shapes from small ones.
Scale operates on many levels. From the level of veins in the leaf, you jump up to the level of leaves on the tree, and then trees in the forest. Similarly, there’s a pattern of curves surrounding the pupil of the eye with iris, white, eyelids, and brow, and there’s the pattern of eyes, nose, mouth, and ears in a face; there’s the pattern of small rectangles and squares that make up a door, and the larger pattern of squares and openings that make up the façade of a house.
Visually and practically, changing scales move our eyes from center to center – as the veins in a leaf move nutrients from leaf surface to stem and as branches move nutrients from leaves to trunk, etc. Similarly, different sizes of panels in a door move your eye from one plane to another, from door to frame to wall.
Compositions of multiple centers, like leaves on the tree, relate the whole to the parts, and provide balance. This allows us to shift our focus to the boundaries where transitions happen. Boundaries mark the limits of growth. Look at where leaf meets branch, or where branch meets trunk. On a practical structural level, this is where the tree changes function. Where leaf meets branch, materials change from production to support: there’s a clear break between the leaf, which will die and fall off in a single season, and the branch, which will live and grow for years. Similarly, where branch meets tree, the trunk needs extra material to support the weight of the branch. Typically, such functional changes create visual changes, patterns that suddenly shift in size, number, texture, or color.
Biologists talk a lot about the “boundary effect” in transitional zones between different kinds of habitat, where life increases in complexity, variety, and richness. The same principle applies to visual analysis, where boundaries create richer habitat for the eye. The edges of leaves, for example, may be serrated, toothed, or even just very slightly curved; there’s more going on, things are moving, rhythm and repetition increase. That movement attracts our attention in the same way that a running rabbit attracts the hawk to strike.
 Like biology or religion, interpretations of visual boundaries vary according to the interpreter. Paul Grillo, an architect who wrote a 1960 book called Form, Function, and Design, attacks border decoration as the physical expression of pathological fear: “the fear complex, with its complement, the security urge, can be considered as the pathological syndrome of our civilization. In the field of pure design, it reveals itself in many ways:
“For instance, the fear of a clean meeting of the vertical and the horizontal may be traced as the essential reason for the moulding...”
After equating mouldings with fear, however, he explains that mouldings also alleviate fear by “prolonging” the transition between vertical and horizontal.
“Pure design” invites such contradiction because it separates aesthetics from function, and divides objective reality against subjective experience. By way of comparison, Chris Alexander, another architect who takes a more biological and scientific perspective, notes that life grows and proceeds by repeating units that not only duplicate themselves, but do so in distinct, rhythmic, musical patterns which change in tempo, intensity, etc. He uses this logic to argue for visually complex boundaries such as those made by moulding, or varied thicknesses of trim around doors and windows.