I'm no expert on cultivars by any means, I'm just going by my understanding of them!
For example, here's the cultivar description of "Leah Wilkerson" from the ICPS website:
Sarracenia ‘Leah Wilkerson’Submitted: 12 April 2004
This naturally occurring Sarracenia hybrid was a chance find while visiting a bog on private property---with permission---in Walton County, Florida in May of 2002. Actually it was hard to miss this outstanding S. x moorei cross, as it stood head and shoulders above all the Sarracenia flava and Sarracenia leucophylla plants in the bog because of its sheer size. I have observed this plant in the field for two years and in cultivation for one year. Unlike most S. x moorei crosses, it displays unbelievable hybrid vigor. The original genet measured over two meters (six feet) across with more than fifty pitchers; the tallest of these measured 130 cm (50 inches) tall, while the heights of the majority of the other pitchers measured between 86-97 cm (34-38 inches). The average lateral measurement of the hood was 17 cm (6.5 inches).
In addition to its gigantic proportions, this hybrid is outstanding because of its stunning coloration. The lower three quarters of the pitchers are lime green, and the pitcher tops are lemon yellow with large areoles and light red veining. The ala is lined in red. The nectar roll is pronounced, undulated and mottled with red; this pigmentation becomes more solid near the column, and forms a throat blotch typical of the S. flava var. rugelii parentage. The lid is particularly colorful with an overall pale yellow color (verging on white) with regularly spaced strong red veining throughout. From a distance the lid takes on a peachy golden cast. The edge of the lid is edged in red and ruffled, typical of the S. leucophylla parent.
This hybrid produces most of its pitchers in the spring---obviously an influence from the Sarracenia flava in its ancestry. In cultivation, these spring pitchers regularly reach 86-91 cm (34-36 inches) in height. A second flush of pitchers is also produced in the fall, and as in S. leucophylla, these pitchers are even larger, measuring up to 96 cm (38 inches) tall.
The cultivar name honors Mrs. Leah Wilkerson, who has lived her entire life on the property where this plant occurs. About one-third this property is bog habitat. As her father before her did, Mrs. Wilkerson makes sure that the wire grass pasture gets burned every winter. While the family conducted these burns to maintain the pasture for livestock, they were providing the exact conditions to allow the other native plants to thrive, including the pitcher plants. So the name Sarracenia ‘Leah Wilkerson’ honors both Mrs. Wilkerson and her stewardship.
Vegetative propagation is necessary to maintain the unique features of this hybrid. I obtained written permission to collect a sample of this specimen, and it is presently in a private tissue culture lab. Those interested in obtaining specimens of this plant should contact me using the address below.
As I read it, you MUST use vegetative propagation to propagate this plant. If Brooks Garcia patented this plant, then we'd have to have his permission to reproduce the plant. If you collect seed from 'Leah Wilkerson' then the offspring are NOT 'Leah Wilkerson' going by the cultivar description and the patent wouldn't cover seed grown progeny of the parent. As a result, if you were in Wilkerson's Bog and you saw many plants similar to 'Leah Wilkerson' they wouldn't be 'Leah Wilkerson'.
There are some cultivars that can be reproduced from seed based on the cultivar description (such as D. 'Ivan's Paddle') and those would come under the patent if that plant was patented. That being said, I disagree with the statement "cultivar registration doesn't go so far as to get into genetic compositon of a plant." I feel it does, because if it did not, there would not be limitations placed on how the cultivar could be reproduced in order to preserve the qualities of the particular specimen. The only way to maintain the qualities that made this plant worthy of cultivar status is to maintain the genetics that control the qualities.
An example: there's named Sarracenia cultivar 'Daniel Rudd.' I've heard allegations that many of the plants circulated as 'Daniel Rudd' are not the real thing. Someone attempted to cross the same species to recreate the cultivar and selected a plant similar to the cultivar but it's NOT the cultivar. Another example is S. oreophila 'Don Schnell.' The only exisiting specimen of this cultivar was lost before it could be reproduced, so it's lost forever.
I hope what I think I know about cultivars aren't too off base and how all of it ties in to the issue of plant patenting. I believe that the plant is only covered by the patent if it fits the cultivar description.
If my understanding of cultivars is not correct, PLEASE somebody correct me! ;-) I also hope this is clear 'cause i was trying to type this out in chunks between working with clients since I'm doing this at the office!