Editing Philodendron (section)

===Roots===
Philodendrons have both [[aerial roots|aerial]] and subterranean roots. The aerial roots occur in many shapes and sizes and originate from most of the plant's [[node (botany)|nodes]] or occasionally from an internode. The size and number of aerial roots per node depends on the presence of a suitable substrate for the roots to attach themselves. Aerial roots serve two primary purposes. They allow the philodendron to attach itself to a tree or other plant, and they allow it to collect water and nutrients. As such, the roots are divided [[morphology (biology)|morphologically]] into these two categories. Aerial roots used for attaching to trees tend to be shorter, more numerous, and sometimes have a layer of root hairs attached; those used for collecting water and nutrients tend to be thicker and longer. These feeder roots tend to attach flush with the substrate to which the philodendron is attached, and make their way directly downwards in search of soil. In general, feeder roots tend to show both positive [[hydrotropism|hydrotropic]] and negative [[heliotropic]] behaviors. Characteristic of roots in philodendrons is the presence of a sclerotic hypodermis, which are cylindrical tubes inside the [[epidermis (botany)|epidermis]] that can be one to five cells long.<ref name="French1">{{harvnb|French|1987|pp=891–903 }}</ref> The cells that line the sclerotic hypodermis are elongated and tend to be hardened. Underneath the epidermis is a unique layer of cells in a pattern of long cells followed by short cells.