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Name: Hippodendrus trees (Hippodendrus spp.)
Creator: Cube67
Ancestor: Robust Purpleblade
Habitat: Glicker
Size: 1 - 6.4 m tall
Support: Cell wall (cellulose), Silica fibers
Diet: Photosynthesis (sun-loving (shade-tolerant))
Respiration: Passive (stomata)
Thermoregulation: Ectotherm
Reproduction: Sexual (dioecious, airborne spores, viviparous (seedlike propagules))

Having already evolved into treelike forms before, the remaining robust purpleblades very quickly diversified after the End-Binucleozoan Atmospheric Disturbance killed off the trees of Glicker. This bounce back towards large sizes resulted in the evolution of the genus Hippodendrus.

The traits that all Hippodendrus trees share in common are fairly conserved from their ancestors. For the most part, they are scaled-up robust purpleblades, retaining a simple morphology consisting of a thin cone-shaped stalk with periodic rosettes of leaves. One of the few noticeable traits unique to and common amongst all Hippodendrus trees is a higher number of leaves; leaf count has increased by an order of magnitude in order to absorb more light. That said, they don’t produce very much shade, and as a result few if any Hippodendrus species have evolved to grow optimally in the shade cast by other Hippodendrus. Many species can still grow in partial shade even as adults, but they become thin and rangy in their search for light.

Also like their ancestors, Hippodendrus trees have fibrous siliceous deposits in their tissues. These deposits serve the dual purpose of driving away would-be predators and providing structural support. Since the silicic acid necessary to build silica deposits is abundant in most substrates, Hippodendrus trees are able to adapt surprisingly well to varying soil types. The only soils where Hippodendrus trees struggle to make adequate silica deposits are mostly organic soils like peat and, ironically, coarse-grained sand, since larger sand grains dissolve into silicic acid more slowly than smaller grains would. In these habitats, regular Hipodendrus trees often become stunted in their growth, and the few species adapted to these conditions produce thicker cell walls to compensate for the would-be mechanical strength of the more extensive silica deposits possible in other regions.

The propagules (sometimes called “seeds”, despite their lack of a true endosperm) of Hippodendrus trees are spherical, and range from 1 to 3 centimeters in diameter. When dropped from the parent tree, these propagules have a thick coating of proteins and dead cells that does not degrade. This coating appears dark purple when alive, but turns dark grey or brown some days after being dropped. The embryo inside is also provided with a significant amount of nutrients to jumpstart its development, and can stay dormant for a couple of years. While not true seeds, these attributes make Hippodendrus propagules quite seedlike in composition and function. Propagules of Hippodendrus trees living in dry areas generally only have the dispersal options of being rolled around by wind or moved around by local fauna, but propagules of species in wet areas often roll into rivers and get carried far downstream. The spaces between the bases of Hippodendrus leaves are often just wide enough for their propagules to drop between them and not become stuck.

(POST-SUBMISSION NOTE: for taxonomic clarity, it may make sense to italicize the word Hippodendrus in the description when this species is posted to the wiki. Also, Hippodendrus means “horse tree”, and is a reference to the plant’s vaguely horsetail-like leaf arrangement.)

This post has been edited by Cube67: Feb 20 2023, 06:09 PM

This is great, lots of ways this lineage could go. My only note is that clay soils should usually be very rich in silica. The mineral components of soil (sand, silt, clay) are basically always high in silica, and it is organic-rich soils that lack it (muck, humus, peat, etc). Although very sandy soils can still be silica-poor because it isn't as bioavailable (less weathered so the SiO2 is locked up in the rocks and dissolves slowly due to low surface area:volume). I didn't think of this when I made the description for the ancestor (my bad).

Edited the silica part. Does this seem more accurate?

QUOTE (Cube67 @ Feb 20 2023, 09:10 PM)

Edited the silica part. Does this seem more accurate?

Yep, this looks good to me.