Re: Ping theories

Jan Schlauer (zxmsl01@studserv.zdv.uni-tuebingen.de)
Thu, 17 Mar 1994 19:59:05 +0100

Barry

>I had been struck by your interpretation of Ping
>morphology, that the plant is a rosette of leaves, terminating in a long
>*pedicel* (not peduncle) emerging from the rosette, at which point axillary
>buds produce new growth and that is how the plant continues after flowering.
>
>That is your stance, correct?

More or less - I think the rosette is terminated by an inflorescence rather
than by a single pedicel. The inflorescence is a (sometimes extremely)
reduced raceme with condensed scape and internodes. The apical bud of this
raceme does abort (most apical buds of racemes do so). The new rosettes
(and if present, also the gemmae) are formed from axillary buds.

>I had been thinking how this theory made sense, because occasionally
>one of my Pings will develop two crowns in the rosette which may take a
>few years to separate fully. This usually happens after flowering, presumably
>when two axillary buds have been activated.

This is what I think, too.

>I had also been thinking about how boreal Pings produce hibernacula
>(winter resting buds) and how at this time of the year they often
>produce gemmae buds as well. I was thinking that I don't recall ever
>having seen a plant produce these gemmae buds if the plant was grown from
>seed and had not yet flowered for the first time. In other words, flowering
>seems to be a prerequisite for gemmae production.

Normally this is the case, but not really always (especially in vitro there
is abundant gemmae production by seedlings even without using any hormones,
and the plants flower very rarely).

> Since gemmae buds
>probably form from axillary buds, would it make sense that when a Ping
>germinates, there is so much apical dominance from the auxin at the
>apical meristem that there is no or little chance of gemmae production,
>but then after flowering, apical dominance is lost, an axillary bud
>starts up new rosette growth, and at the same time gemmae bud growth
>is initiated.

This does quite certainly make sense (and it does completely agree with my
own ruminations).

Kind regards
Jan