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Extension > Garden > SULIS > Design > The Landscape Design Sequence > Concept Plans and Lines > How Line Forms Dictate Space and Style

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How Line Forms Dictate Space and Style

Tim Ripp


Design principles are the fundamental guidelines every landscape designer should use as a basis for creating their plans. These principles include scale, line value contrast, lettering and line forms. There are five basic line forms:

  • Rectilinear
  • Arc and tangent
  • Arc and radii
  • Arc and arc
  • Curvilinear
Line forms emphasize real and imaginary lines and play an important role in the creation of large and small spaces within a landscape. In landscape design, spaces define "outdoor rooms" and the movement and flow between those rooms. Line forms dictate traffic patterns within the landscape and help visitors guide visitors through the various spaces. Placement of hard features will also depend on the line forms used and the flow they create.

Each type of line form -- rectilinear, arc and tangent, curvilinear, etc. -- will create spaces differently and the designer should be aware that the line form they choose to define a space will depend on the design style they are trying to achieve and the desired experience. Blending styles and remembering that "form follows function" allows a designer to accentuate the best elements within a landscape.

Line Forms and Styles:

Rectilinear Line Form


Grid: the pattern created by lines running side by side (parallel) and intersecting with lines running at right angles (perpendicular) to the parallel lines.


  • No arching or curved lines;
  • Line segments may be of any length or various lengths;
  • All lines are straight;
  • All lines are either parallel or perpendicular to one another;
  • Lines intersect at 90-degree angles;
  • Promotes a regular grid pattern style
  • The intersections of this grid pattern dictate gathering spaces;
  • Rigid style;
  • Very formal style;
  • Typically symmetrical;
  • May create the feeling of cold and unwelcoming if underdeveloped.
Figure 1
Figure 1: Example of a grid pattern in a rectilinear line form. (Illustration by Tim Ripp)

Figure 2
Figure 2: Example of rectilinear form in a landscape design plan view. (Illustration by Tim Ripp)

Arc and Tangent Line Form

Arc: any portion of a circle or ellipse.

Tangent: a straight-line segment that meets an arc, but does not break the curve.


  • A series of arcs connected by straight-line tangents;
  • Only two types of line segments: straight tangents and arcs;
  • Arcs may be either circular or elliptical;
  • Lines that do not meet are either straight or intersect at 90º angles;
  • Lines can be either parallel or perpendicular;
  • Lines extending beyond an arc will form a grid;
  • Tangents cannot intersect directly;
  • Circular arcs will have a constant radius, but circles may differ within the design;
  • Elliptical arcs have a slope that is ever increasing / decreasing.
  • Less formal;
  • May be symmetrical;
  • Patterns. Of straight-line tangents express rectilinear form;
  • Straight-line tangents promote movement;
  • Arc segments dominate the design;
  • Curves increase the overall flow within the design;
  • Arc areas promote pause and gathering areas.
Figure 3
Figure 3: Example of arc and tangent form. (Illustration by Tim Ripp)

Figure 4
Figure 4: Arc and tangent form used for concept lines in a landscape design. (Illustration by Tim Ripp) Arc and Radii Line Form


  • Two major line segments, straight lines and arcs which are a portion of circles and ellipses;
  • Straight-line segments must radiate from the center point of a circle or ellipse;
  • The straight-line segments constitute the radius and must be complemented by the presence of at least some portion of the circle or ellipse;
  • Straight-line segments must intersect circle or ellipse at an angle perpendicular to the tangent of that arc;
  • All radii must intersect at right angles, or run parallel or perpendicular to each other;
  • Radii can be of varying lengths;
  • Arcs can be of any length and size;
  • Straight-line segments will form a grid pattern similar to the rectilinear form.
  • Formal style due to the grid pattern that develops;
  • Arcs tend to promote gathering spaces;
  • Radii dissecting arcs tend to extend space within the arc beyond it;
  • Straight-line segments connecting two or more arcs will often promote movement between spaces.
Figure 5
Figure 5: The form of arc and radii (Illustration by Tim Ripp)

Arc and Arc Line Form


  • Utilizes only one type of line segment;
  • Line segments are always portions of arcs, either circles or ellipses;
  • Circular arcs will have consistent radii;
  • Elliptical arcs will connect all major axis with the end of minor axis;
  • Circles and ellipses may be of varying lengths within the design;
  • Arcs may intersect in a variety of configurations as long as the relationship of the intersections remains consistent within the design plan;
  • Informal overall design concept;
  • Configuration of overlapping circles and ellipses which open into one another and promotes sharing of space;
  • Although informal, the style of this type of line form is not necessarily natural of flowing;
  • Greater space within an arc promotes its use as a gathering space;
  • Smaller arcs and the space within an arc promote movement.
Figure 6
Figure 6: Example of arc and arc line form. (Illustration by Tim Ripp) Figure 7
Figure 7: Arc and Arc line form as a concept line in a plan view. (Illustration by Tim Ripp)

Curvilinear / Biomorphic / Organic Line Form


  • Line segments consist of only one type of spatial edge;
  • All spatial lines are curving;
  • All arcs have consistently changing radii;
  • Arcing lines may increase / decrease along the direction of movement through the plan;
  • Arcing lines may change orientation and direction so as to never re-curve or close upon itself;
  • Line segments can be of any length.
  • Very informal;
  • Natural, flowing lines;
  • Reflects forms found in nature;
  • Movement of free-form lines in the landscape offers more possibility for exploration and discovery;
  • Tends to blend manicured landscapes into more natural environments;
Figure 8
Figure 8: Example of curvilinear / organic line form. (Illustration by Tim Ripp)

Figure 9
Figure 9: Curvilinear line form in a landscape design plan view. (Illustration by Tim Ripp)


Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida "Basic Principles of Landscape Design", Dewayne L. Ingram. June 1991.

Ingles, Jack E., Landscape Principles and Practices, 5th edition, Delmar Publishing, Albany, New York. 1997.

Nelson, William R. Jr., Landscaping Your Home, University of Illinois, Champaign, IL. 1975.

Pitt, David, "Making Landscape Space", 1997 core course hand-out, LA 5211, College of Landscape Architecture, University of Minnesota, Minneapolis, Minnesota.

Pierceall, G.M., Residential Landscape, Graphics, Planning and Design, Reston Publishing Company, Reston, Virginia. 1984.

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