I have alluded to the epiphytic plants which are so abundant in the tropics, and which add so greatly to the gorgeousness of the forests there. The most remarkable, or, at all events, the best known, of these are the _Orchideæ_, to which, as I have already had occasion more than once to speak of them, I shall do little more than refer here. These establish themselves in the forks, upon the greater limbs, and even in the roughnesses of the bark of the trunk, adhering by their long, interlaced roots, which look like knotted whip-cord, and forming their bunches of psuedo-bulbs, whence their succulent, thick, but elegant leaves project,--a great tuft of verdure; and their fantastic flower-scapes wave in the air or droop with their weight of gorgeous bloom. Thus they derive their nourishment from the humid atmosphere alone, being dependent on the friendly tree only for support and elevation. Humidity seems essential to the vigour of these and most other forms of parasitic vegetation. In the deep shady, gloomy forests of Java, which constitute the zone of vegetation around the base of the mountains, these plants abound, where the air is heavy and damp with the vapours that cannot ascend, and where the density of the foliage is almost frightful; where heat, moisture, and a most extraordinarily deep and rich vegetable soil combine to produce wood of a fungus-like softness, and an inconceivable abundance of twining plants and epiphytes. In those forests, more especially where huge fig-trees constitute the principal part of the timber, intermingled with the most tropical forms of vegetation, such as _Sterculiaceæ_, _Sapindaceæ_, and _Artocarpeæ_, tufts of _Orchideæ_ attain a vast size and luxuriance, in company with Aroideous and Zinziberaceous plants.[228] In Demerara, Mr Henchman found masses of _Oncidium altissimum_ and _Maxillaria Parkeri_ of wide dimensions, and so densely growing as to defy any attempt at intrusion; and on the Spanish main he saw the _Epidendrum_ known as the "Spread Eagle" clasping enormous trees, and covering them from the top to the bottom.