private final void tick(double secondsPassed)
							{
								if (isLeaf)
									{
										// NOTE: seedlings do not have shadows
										// hence BLACK shadow
										energy += Hub.simWindow.sim.photosynthesizeAt(getX() + Rand.double_((int) leafSize / -2, (int) leafSize / 2), (int) y, genes.leafColour, shadowColour)
												* secondsPassed * fractionGrown;
									}
								else
									for (Node n : daughterNodes)
										n.tick(secondsPassed);
							}