Those are called stem cloves, and they are fairly common on artichoke type (soft neck) garlic varieties. Soil & climate conditions influence the formation of stem cloves; some years I get a lot of them, some years little to none.

Those cloves are worth planting, because they may leave behind soil-based diseases which can follow the bulbs. Some of the stem cloves I planted formed mid-sized bulbs the first year.

Thought I said it clearly..."Those cloves are worth planting..."

Because the stem cloves are above the ground & often enclosed within the pseudo stem, they are far less likely to have come in contact with the soil. The problem with garlic is that if you plant an infected bulb clove, any disease present on that clove is passed on to the bulb which grows from it, and to the next bulb from that, etc. Over time, diseases can accumulate which weaken the stock.

Some pathogens can travel throughout the plants, and those could still be present in the stem cloves. Viruses are an example, and those are difficult to eliminate.

However, other pathogens - and some pests, such as garlic bloat nematode - are passed on by direct contact with infected stock, or infected soil. Because those organisms may not be present on the stem cloves, they offer an opportunity to "start over" with stronger, more disease-free stock.

The same is true of the bulbils formed by hard neck garlic varieties, and some garlic growers use that method to periodically renew their stock. The stem cloves are just far less common.

Thanks for the very informative post. I truly enjoyed it, and I'm sure others will to. The reason I was confused was you said " Those cloves are worth planting, because they may leave behind soil-based diseases which can follow the bulbs." I guess that I didn't read it close enough to catch the difference between cloves (stem cloves) and bulbs. Using stem cloves, how many seasons is it until you get something like a regular bulb? Thanks again.

Point taken, Wolverine, I probably should have said "those stem cloves..."

Most of the stem cloves I planted were pea sized or larger. They formed 1-1.5" divided bulbs the first year, only slightly smaller than the bulbs of the same variety grown from bulb cloves. That surprised me - there were virtually no rounds. That first-year bulb formation is about what I would expect from planting the larger rocambole bulbils. The cloves from those first-year bulbs look like they will produce near-normal bulbs this year, and should be maximum size after 3 years. It appears those bulbs will exceed the size of the parent stock grown from bulb cloves.

Stem bulbils are also common on many strains of Japanese. About 3/4 of mine showed at least one this year and several of them as many as 3 or 4. All are quite large as bulbils go. Zeedman is quite right in that those bulbils will usually produce a small cloved bulb the first year very much like many rocambole bulbils do. Two or three years to size them up is also about right, just be sure to always plant back the largest cloves. My Japanese produces very large stem bulbils.

I wonder about the Japanese whether late planting somehow causes the scapes to essentially bloom inside the stems... That is what some of these look like in my Japanese. On one what looks like a more or less aborted scape broke out the side of the stem and produced bulbils on its end. I like Japanese, but was wondering whether I need to replace my stock. What I have gets one more year. This fall it gets set much earlier, perhaps in late September this time rather than early November like last year. Same for my turban (Xian), which failed big time to get beyond rather small rounds.