This is a phylogenetic tree viewer. All options associated with it do not change the tree information in any way, only the way in which it is presented.

The user can choose the style of tree to be returned:

• Tree diag: draws an unrooted tree.
• Cladogram: nodes are connected to other nodes and to tips by straight lines going directly from one to the other. This gives a V-shaped appearance.
• Phenogram: nodes are connected to other nodes and to other tips by a horizontal and then a vertical line. This gives a particularly precise idea of horizontal levels.
• Curvogram: nodes are connected to other nodes and to tips by a curve which is one fourth of an ellipse, starting out horizontally and then curving upwards to become vertical.
• Eurogram: (so-called because it is a version of cladogram diagram popular in Europe). Nodes are connected to other nodes and to tips by a diagonal line that goes outward and goes at most one-third of the way up to the next node, then turns sharply straight upwards and is vertical. Unfortunately it is nearly impossible to guarantee, when branch lengths are used, that the angles of divergence of lines are the same.
• Swoopogram: connects two nodes or a node and a tip using two curves that are actually each one-quarter of an ellipse. The first part starts out vertical and then bends over to become horizontal. The second part, which is at least two-thirds of the total, starts out horizontal and then bends up to become vertical. The effect is that two lineages split apart gradually, then more rapidly, then both turn upwards.

Another option is the tree growth option, which determines what the

• Horizontal or vertical: specifies orientation of a tree.
• Regular: will make an unrooted tree have regular angles. This will make the lines vertical if they are close to vertical, horizontal if they are close to horizontal, 45 degrees if they are close to that, and so on.
• Use node lengths (or not): if a tree has branch lengths, these may be used to specify the length of each node, or not.

The last option is the node position, which will affect the positioning of nodes for rooted trees. It controls the horizontal positions (for a tree growing vertically) of the nodes.

• Intermediate: places a node halfway between its immediate descendants.
• Weighted: places it closer to that descendant who is closer vertically as well.
• Centered: centers the node below the horizontal positions of the tips that are descended from that node.
• V-shaped: designed to yield a v-shaped tree of regular appearance if there are no branch lengths being used. With branch lengths it will not necessarily do so.
• Innermost: chooses a center for the tree, and always places interior nodes below the innermost of their immediate descendants. This leads to a tree that has vertical lines in the center, like a tree with a trunk.