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Ancestor: Nepeta cataria (Catnip)
Common Shortmint
Temporal Range:
Temporal Range:
Evolved: Around 15,000 Yh (By 100,000 Yh)
Extinct: Not yet
Habitat and Geography:
Habitat and Geography:
Location: Southern point of the West Catlandian mountain range, at an elevation where lowland plants struggle and thus there is less competition.
Viable Habitat: At high elevations in subtropical climates where there is adequate rain. Also requires some soil establishment.
Needs:
Needs:
Sun: Tolerance for sun exposure is species and population dependant, depends on if the species or population originated on a primarily North-facing or primarily South-facing slope, and how many other plants are around to shade them out. Species-wide they are generally versatile and adaptable to different hours and exposure levels of sun.
Growth medium: Can tolerate very gravelly soil with low organic matter, but does still require some organic matter in the soil. Needs soil that drains freely, except for a few species that are tolerant of and found around pooling water. Prefers soil pH that is neutral to slightly alkaline, except the species found around pooling water which tend to be more acid tolerant.
Water: While they can outlast droughts of a few months they generally need a lot of rain for optimal growth, between 400 mm and 800 mm per year ideally. Due to the short lifespan and quick reproduction of this plant, there is a lot of local adaptation so some species are tolerant to more rain, some less.
Size: Varies by species, 5cm - 50cm
Life Cycle: The plant grows from nutlets, which are the seed fruits. They appear like seeds, small round and shiny. The nutlets are much smaller and of greater quantity, always in a multiple of 4. This is because the ancestral ovaries starting at 4 each themselves split into 4, and sometimes more, multiplying the resulting seed count but reducing their size greatly. This means although many nutlets are eaten by mice, enough of them still fall into the soil when the seed capsule spills and are lost to the small masticating animals, able to germinate in peace. There are always a few sacrificial seeds. The surviving seeds are able to stay dormant for a number of years if conditions are not optimal for germination.
At flowering, the plants all have very brightly coloured inflorescence in an attempt to attract the few pollinating insects that can be found on the mountain range, who can see the plants easier from the air than the herbivores can from the ground. They are all trying to compete with each other for the attention of pollinating insects, hence the explosion of flower colour and shape variation. This is when the ovaries are fertilised and where the cycle returns to it's starting point.
There are a few species that survive winter as a rhizome. However most species in this genus facilitate population turnover by dying completely once their reproductive cycle is complete, and seeds fallen into the soil are hardy against the frost and snow that falls on the mountains during the coldest months. Rhizomes can spread and sprout new plants, a form of asexual reproduction.
Other: This plant focuses on being short-lived and inconspicuous, remaining low to the ground hidden from obvious sight of herbivores by other plants like grasses or by rocks in the mountain slope. It usually grows a single unbranching stem, though can sometimes produce two or three stems from the roots.
Slightly higher frost tolerance than the ancestral catmint, to cope with the freezing temperatures that can occur at high elevations in the mountain range. However they can still be killed off by extreme ice. When this happens they recover mainly from the soil seed bank during the next favourable season. They may sometimes recover from surviving underground roots, but usually they will die back to make way for the next generation and reduce competition stress on their descendants. This high speed rate of population turnover via sexual reproduction allows them to adapt quickly to changing conditions or cope with the variable terrain if they spread to a different mountain slope with different environmental conditions. This is why there are now simply too many species to list and the genus is described as a whole. There are some species that only exist on their home mountain slope and nowhere else.
Another characteristic of this genus is thicker, more densely packed trichrome hairs especially on the stems. They are stiffer and make the leaf surface feel more bristly. This is a barrier to insect herbivores and makes the shortmint an undesireable lesser choice compared to other plants for the rabbits. At the end of each trichrome is a weak barrier holding back essential oil contained within the trichrome. It is easily ruptured by light physical contact releasing the oil. Although pleasantly aromatic to some creatures, it's very bitter for rabbits to taste and a toxic hazard to caterpillars and other insects.
In the ancestral species releasing the oil would cause the trichrome to lose it's turgidity. This is not the case in shortmint trichromes, which are reinforced structurally so that they are more like a needle and continue to offer a resistive barrier after being touched. It isn't enough to break skin of animals but it is enough to cause very unpleasant abraision sensations on soft flesh like the inside of the mouth. There is some variation within the genus, with some plants forming tougher trichromes than others, and some evolving more towards secreting oil that is harsher, stickier and more volatile.
The stems are short and thick, and have the square cross-section common to many mints. Lateral branches are much less common compared to their ancestor but can still be forced if apical growth is damaged or eaten.
Species and Subspecies:
Species and Subspecies:
Not every species or subspecies will be listed here, as there are well over 50 species within this genus. A small selection will be described.
Mouse's Friend Shortmint - Has larger flowers with stiffer more robust petals nearer the ground and smaller more delicate flowers further from the ground. The upper flowers are pollinated by insects and have a sharper menthol fragrance that carries on the wind. The lower flowers attract primarily mammals, rarely reptiles, and smell more like sugar or honey. The lower flower shape has upturned "handles" for mice to grab hold of while feeding from the crudely hidden nectary. As it does it transfers pollen between anther and stigma when it bumps it's head on them, and carries pollen on it's fur to other flowers it visits. Adding mice to it's pollinators increased it's overall chance of pollination in an environment hostile to insects. In addition to pollinating the mice occasionally leave behind their waste when they stop to feed. This provides precious organic fertiliser which often gets washed out of gravelly free-draining soil.
When flowers begin to open trichromes on the dorsal side of the leaf break down as do the oils within them, to make the leaf inoffensive for mice to step on. However on the ventral side oil-rich trichromes remain intact, so a herbivore who tries to eat the leaf will taste them.
A montane climbing mouse is enticed by the sweet nectar of the mouse's friend shortmint, and unintentionally collects pollen on it's forehead.
Shy Shortmint - Usually found concealed from sight by other plants. The leaves throughout it's inflorescence help it capture more sunlight on grassy or shrubby slopes where they may be overcrowded by other plants for light. They require softer wetter and more organic soil than most of this genus to support their rapid growth and hasty reproductive cycle so are not usually found in nutrient poor, rocky environments but more where plants are already established and have built up the soil.
Because this plant grows quickly it doesn't have as strong defences. Trichromes are fewer and the repellant oil is weaker. The plant is not as tough, much easier to bite and chew. Vegetative growth is rapid and cuts corners that make the plant more vulnerable to herbivores and parasitism. It makes up for this with the speed of growth and the amount of seeds they drop from one pollinated flower, around 64 the maximum of this genus. They can complete their life cycle in a few months, and can sometimes seed three generations in one year.
Because this species is more appetising to rabbits they use a colour of infloresence that is less conspicuous to rabbit colour vision. To those with eyes sensitive to the colour, the petals are bright red. To the rabbits they appear a muddy colour, blending in to dirt, dry grass and weathered bark because rabbits are colourblind to red. Now the flowers cannot be used by rabbits as an indicator of this plant's presence, rabbits must expend more effort to find it.
As a consequence it cannot be seen clearly by bees, although the flower still reflects a little ultraviolet as a hint to them. That said there aren't many bees in their native habitat. The main pollinator is butterflies which can see the red just fine, hence why the lower petal has retained the ancestral shape of a landing platform.
This species is more likely to form lateral branches than others of it's genus, especially if it's growing in a spot unfavourable for capturing light.
Human full colour vision
"Bee vision", ultraviolet shown as magenta
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