Geastrum lageniforme s.l.

For general comments about the genus see https://canberra.naturemapr.org/species/5724.

In Geastrum lageniforme the unopened fruitbody may have an onion-like look, but often the apex is further extended into a pronounced beak. The immature fruitbody then resembles one of those ancient long-necked flasks, called a lagenos in Greek and a lagena in Latin - hence the species epithet lageniforme (and the English adjective lageniform).

When mature the star-like base may measure about 2 to 5 or so centimetres across and the spore sac about 1 to 2 centimetres. The spore sac sits directly on the star-like base. The mouth of the spore sac is surrounded by conical and densely fibrillose structure (technically a peristome). The peristome is surrounded by a circular zone that is usually well-differentiated from the rest of the spore sac.

When dry the star-like arms may be bent in various ways but they do not close in and cover the spore sac as is the case with a few species of Geastrum. The arms consist of three layers. Uppermost is a fleshy layer that tends to show cracks when the fruitbody dries. Below the fleshy layer is a tough, whiteish, fibrous layer and lowermost is the thin mycelial layer. Some soil or fine debris  may adhere to the mycelial layer but it is not densely encrusted with tightly bound soil/debris as is the case with some species of Geastrum. The brownish mycelial layer often cracks radially and you can see the whiteish fibrous layer through those cracks.       

This species is found in numerous countries.

Since some would question the use of lageniforme in Australasia I have qualified the species name with s.l. (a standard abbreviation in botanical works for the Latin phrase sensu lato, meaning 'in the broad sense').

Look-alikes

In the past there had been much debate about the relationships between Geastrum lageniforme, Geastrum saccatum and Geastrum triplex. That’s the subject of the technical note below.

In all three the immature fruitbodies are onion-shaped to lageniform and the mycelial layer is not densely encrusted. In a typical Geastrum triplex the fleshy layer cracks in a circular fashion to form a distinct collar around the base of the spore sac. Such a collar is very rare in the other two. Geastrum triplex can be quite robust – the star-like base reaching up to 20 centimetres in diameter, the spore sac up to 5 centimetres. The others usually reach no more than half those dimensions. Of course, fully mature Geastrum triplex fruitbodies may sometimes be relatively small and then there is obviously scope for confusion, with a microscopic examination needed. In Geastrum saccatum the mycelial layer has a felty texture – not so in the other two species – and the mycelial layer rarely shows the radial cracks.

Technical note

The authors of the paper listed below make the following comments: "Misidentifications concerning G. lageniforme, G. saccatum, and G. triplex are probably the most important species-level taxonomic problem in Geastrum, which has not been resolved yet based on classical morphological traits. While the distinction of G. saccatum can be made through macro- and micromorphology of the mycelial layer (double-layered, with a felted surface), some big and robust G. lageniforme specimens can be easily confused with small and slender G. triplex specimens ... We have not found any reliable traits in the literature to distinguish these “morphologically intermediate” specimens. Those problems led some authors to consider G. lageniforme and G. triplex as conspecific ... Even in the case of G. saccatum, the correct interpretation of the mycelial layer usually requires some experience, especially to separate it from G. lageniforme, and the habit of both species is so close that misidentifications are common".

The authors found that crystals on the rhizomorphs of the three species are markedly different and easily distinguish them. The crystals can be found in the rhizomorphs of both fresh specimens and in those of dried, herbarium specimens. Naturally, the authors strongly recommend that when people collect Geastrums they look for rhizomorphs.

Reference

Zamora JC, Calonge FD & Martín MP, (2013). New sources of taxonomic information for earthstars (Geastrum, Geastraceae, Basidiomycota): phenoloxidases and rhizomorph crystals, Phytotaxa, 132, 1–20. (see page 13).