Start Update 2011-11-07 After carful consideration I have decided that this Dianthus canít be Dianthus carthusianorum because it doesnít produce seeds as it is pollen sterile. At this time I donít know if this is a mutation or a hybrid, but it have been around for a long time. I am now growing Dianthus carthusianorum from seeds and will be posting about it on this thread. Next spring I hope to compare the two forms of Dianthus side by side. End Update 2011-11-07
I have a Dianthus which has been in my family for a minimum of 70 years in the New York City region, which many be Dianthus carthusianorum. Last year I obtained a specimen from my cousin. Using repeated layering of each new shoot, the Dianthus quickly spread to fill a large pot. The Dianthus was overwintered in the pot with no protection except for several feet of snow which covered it for several months.
Height: 15 in. (38 cm) Flower: 1.0 in. (2.5 cm), pinkish-blue color Scent: Extremely Fragrant. Calyxes: Dark purple color with several calyxes in each cluster. Leaves: Blue/Green color. Steams: Blue/Green color with purple band about the stem at the base of each leaf node.
While none of the Dianthus, which was reviewed, was a perfect match, in terms of size Dianthus carthusianorum is the best choice.
Attached is a photograph of the Dianthus take Sunday May 15, 2011. The Dianthus first bloomed a week earlier on Motherís Day Sunday May 8, 2011. More flowers open each day and none have as yet closed. The Dianthus has full Southern exposure and receives sunlight as long as the Sun is visible. The fragrance given off by this Dianthus is delightful and can be smelled from over 10 feet distance.
I have only observed two potential pollinators. The wasp like insect show in the attached photograph taken on May 15, 2011 and a common house fly which did appear to be too interested in the flowers. It is too early for butterflies and I didnít see any bees.
The past weekend I decided it was time to harvest the seeds from what appeared to mature seed pods of my Dianthus carthusianorum. As I started opening each pod I discovered that they contained no seeds. I then harvested all the seed pods and found they were all devoid of seeds.
There were still a few flowers on the Dianthus and when I inspected them I found that they contained no stamen. I then inspected that close-up picture of the insect pollinator which I posted above and realized that I had overlooked the obvious; my cultivar of Dianthus carthusianorum is seedless because there is no pollen production. This explains the long bloom-time I had observed and why this Dianthus has been so stable over the last 70 years. This Dianthus bloomed so early there no other nearby Dianthus which could have served as a pollen source. If my identification of Dianthus carthusianorum is correct, this Dianthus must be a cultivar and not a species as its survival in the wild would have been difficult.
This Dianthus continues to produce an occasional flower and I have Dianthus amurensis (Siberian Blues) and Dianthus caryophyllus (Carnations) which are in flower and could be a pollen source. It would be interesting to see if any hybrid seeds can be produced. I would like to locate a Dianthus caryophyllus which are grown from seeds and compare the two cultivars.
I have posted before on pollen-sterile seedless Carnations and why they are of value in the cut flower trade. Has anyone had any experience with other lines of pollen-sterile seedless Dianthus?