From Remilia is Marisa, a Remilia with a stalk on her head, inexplicably bearing two Marisas in addition to a Reimu.
The stalk is a branch-like growth that grows out of the yukkuri's head, just above the forehead. It is used in the most common form of Yukkuri reproduction- stalk-type pregnancy. The baby yukkuris grow on the stalk like fruits until they are mature enough to be born, at which point they drop like fruits and are able to live as normal yukkuris. The stalk is then usually fed to the baby yukkuris. Exactly why this is hasn't yet been explored in great detail, but it could be that the stalk contains vital nutrients and passes on vague information and memories.
The main difference between this and the chin live birth is that the stalk method allows for multiple yukkuris to be born.
The most common occurrence is for a single stalk to grow, and between 3 to 7 yukkuris to grow from the stalk.
However, there are cases of multiple stalks growing. But since most of those cases involve the infamous Yukkuri Alice, and thus were not likely consensual, rarely do these multiple stalks ever bear healthy Yukkuries all the way to term.
From this, it can be gathered that the stalk is like a leech, and sucks out nutrients from the mother. This also explains why mothers with multiple stalks often die looking like blackened, withered husks. If a Yukkuri work features a mother living off food stores with the rest of her family, the "father" and any existing children may sacrifice some of their share of the food so that the mother can eat the most possible to sustain the stalk. Growing a stalk and bearing yukkuris on it takes a certain amount of nutrients, and if a yukkuri that is too young or too weak grows a stalk, it may be in danger of malnutrition and death.
Many artists (Clammbon, Pixely guy, DOS) have drawn both stalk-type and chin-live births, so they are not considered to be mutually exclusive to yukkuri fanon. However, it is very rare for a yukkuri to have both a stalk and chin birth at the same time. (Occuring only in the Kind Mother Marisa story).
The stalk is described as being bitter and with an hard, vine-like texture, so much that koyukkuri can't bite through it unless the mother yukkuri softens it by chewing. That's actually a good thing, as it will prevent the koyukkuri from spoiling its tastebuds, making it able to enjoy and eat the simple food a wild Yukkuri can hunt hunt in the wild, whereas if it tasted sweets and soft foods shortly after birth it would refuse anything else, and starve itself to death.
Also, the stalk, much like the mother's milk for mammalian, is ripe with substances boosting the immunitary defences of the koyukkuri.
However, under duress, an human owner may substitute the natural stalk with stalks bought from the Factory or a Yukkuri Pet Shop and steamed broccoli with just a small quantity of sugar water to soften them (emulating yukkuri's saliva): the tangy taste and the texture feel similar to the stalk.
As a funny sidenote, despite being "sprouted" at the same moment, after a stalk pregnancy the koyukkuri will still identify themselves as "widdle" and "big shishters", with the "older" sibling being the first to detach.