Liana

Liana (Russian: Лиана) are strange, part-plant part-animal, tentacle-like species. They are encountered only in the library in Metro 2033 and in Metro: Last Light in the swamp, as well as some parts of the level "Garden".

Overview
The liana are organisms consisting of several parts. Their main body of tissue is a large, undifferentiated grayish-green mass which appears to cling to walls and other surfaces inside the library. This tissue is very widespread but poses no threat to Artyom. It will bleed or ooze when shot or stabbed, but cannot be destroyed. In some places where the body tissue grows across ceilings, it develops long tentacles which will sway and wave continuously. When approached, these tentacles will partially coil. If Artyom comes closer, they will lash out and strike, dealing lethal damage.

The tentacles have a fairly large reach and, due to their locations in narrow hallways, tend to be hard to circumvent. A good way of getting past these obstacles is to shoot them - a single shot is all that is necessary, and will cause the tentacle to curl up to the ceiling for a short period of time. Artyom could also sprint right past them altogether, not giving them enough time to attack. Like the main body tissue of the liana, the tentacles will bleed when shot, but cannot be defeated permanently. Both the attacking tentacles and the visual appearance of the main body of the liana bear some resemblance to the biomass.

Liana commonly have small buds on them. These buds are seen in small clusters on the walls and floor throughout the library and other places in the game. These green glowing, similarly to the radioactive mushrooms, wriggle constantly, and appear to emit puffs of harmless spores.

Liana are possibly evolved from potted plants that used to be around in the library, and may be growing through the ceiling, down from the floor above. The bloody red tip on the tentacles bears resemblance to the Nepenthes carnivorous plant, including the bright red coloration to attract prey. In the book, Ten says they are irradiated house plants known as morning glories.

Liana are the only mutated plants that are hostile to the Artyom in the game.

Appearance and behavior
About a dozen appear in the level “Library”. Liana use their tentacles to attack, and only do so if Artyom stands near them too long. If touched or shot, the tentacle will pull itself up; this is usually a sign to move as it is getting ready to attack.

In Metro: Last Light, liana will make few appearances in the "Sundown" and "Garden" levels. During these levels, be careful when looking for supplies, because they tend to live next to dead bodies which have supplies and are sometimes hard to detect, especially in the garden, where it has similar body color to the background. Liana will attack if Artyom gets too close and in Last Light, its attack delay seems to be shorter than 2033. If one rushes without checking the ceiling, it is more likely to be on the receiving end of its powerful tentacle strike.

In the Faction Pack DLC, lianas make their return in the Great Library mission, which is a revisit of the Metro 2033 level. Here, their layout is slightly different from the first entry, so be careful when searching the main building.

Also in the Redux version of Metro 2033, the layout of the liana in the Library level is slightly different from the original. Artyom may need to shoot them to gain some time to move past them, as its behavior is identical to the Last Light version. Also, there will be one more in the room where Danila opens the door for Artyom, thus its advised to shoot it rather than being trapped in the room and let it attack him.

Tactics
Lianas only use their tentacles to attack and will not chase; the best method is to just run past them in order to avoid the attack. However, you have to know where you are going because stopping in the middle of two to four lianas could be fatal.

The use of weapons, especially inaccurate weapons such as shotguns, is not recommended as Liana cannot be permanently defeated. Firing at them will only waste resources and time. Unless you want to gain time to get past, one round for each liana will be sufficient. Keep in mind that you only have one chance to get passed. Sometimes the tentacle will not be lowered after being shot, but generally the Liana will be immune to gunfire after being shot once.

In the Novel
Librarians in the novel do convert a large amount of rooms into gardens for mutated plants, most often referred to as mutated morning glories. Vines are also encountered by Artyom and Danila in one room which they have to fight through, but these remain plantlike and do not attack.

Large dangling plants are encountered by Artyom in the library's card catalogue described as being as thick as one's arm and made of a greasy luster, they are covered in huge flowers that eject strong pollen causing Artyom to feel faint. They are mentioned as swaying slightly but it is stated it is unknown whether this is due to the wind or their own momentum.

Trivia

 * It's unknown from what type of species the liana actually mutated. By appearance, a plant species seem to be the prime candidate. Although there is no known plant species with this type of 'hostile/aggressive' behaviour with such accelerated movement ability, all of these abilities could easily be connected with the extreme rates of mutation.

Lianen Лиана