Thistle-ish plant in Texas

Question

I found the plant below in Fort Worth, TX at the end of March this year, and can't identify it. It looks a bit like a basketflower, or some other thistle-like plant. It was the only one growing where I found it, and, in several years of frequently walking the area, I have never seen another that I recognised as being the same. I apologise for the washed-out quality of the top of the plant in the first picture; I couldn't get a clearer shot with a cell-phone camera in very bright sun.

The plant was probably about 2 feet tall, and the main part that looks like it will eventually flower was about the width of, and half again the height of, my clenched fist.

Answer 1

I deleted my previous answer (which was correct but didn't ID the growth on the top) And am going to attempt to clear up all the issues related to this question and the image of the plant you provided

The plant in the image you gave is in the genus Salsifies (Tragopogon):

Western salsify has linear, grass-like leaves that clasp the stem at the base. Prior to bolting and flowering, the leaves can be readily mistaken for grass. However, they have a smoother and more rubbery-like feel than grass leaves, have hairs in the axils, and exude a milky juice when broken.
Source: https://www.montana.edu/extension/invasiveplants/documents/publications/extension_publications/Western%20Salsify_revised%202017.pdf

There are multiple salsify species that fit the plant in the image, but only one of which is in the Texas range. (Source: Tragopogon-dubius range map, Tragopogon range map)

The plant can be narrowed down to the species Yellow Salsify (Tragopogon dubius)

Tragopogon dubius (yellow salsify, western salsify, western goat's-beard, wild oysterplant, yellow goat's beard, goat's beard, goatsbeard, common salsify, salsify) is a species of salsify native to southern and central Europe and western Asia and found as far north and west as northern France. Although it has been reported from Kashmir and India, recent evidence[citation needed] suggests that specimens from these areas may be a different species. Western salsify has been introduced into North America where it has become widespread, being reported from all the continental United States except for a few in the far south-east, and all provinces of Canada except Newfoundland and the northern territories. Source: https://en.wikipedia.org/wiki/Tragopogon_dubius

The plant has a strange structure on the top, the cause of which was being debated. After some research it appears to be a case of Witch's Broom Disease also known as Phytoplasmas
And according to this Wikipedia article:

Witch's broom or witches' broom is a deformity in a woody plant, typically a tree, where the natural structure of the plant is changed. A dense mass of shoots grows from a single point, with the resulting structure resembling a broom or a bird's nest. It is sometimes caused by pathogens.

Until recently this disease was thought to be only found on trees. But recent discoveries show that this disease is found on a range of plants. Interestingly enough in Novemeber 7, 2015 this disease was first reported to be on Tragopogon dubius (reported in Iran) and was confirmed after DNA tests.

In a survey conducted for phytoplasma diseases in 2014, T. dubius witches' broom disease was observed in vineyards and green areas of Bajgah and Zarghan localities. The characteristic symptoms of T. dubius witches' broom were flower virescence and phyllody, crown proliferation and witches' broom. Since the symptoms were suggestive of phytoplasma infection, plants were assayed for presence of phytoplasma by PCR amplification. Total DNA was extracted from 0.3 g of midrib tissue of four witches' broom affected and two symptomless T. dubius plants (two plants per location), using the procedure of Zhang et al. Total DNA samples were tested by both direct and nested PCR assays using phytoplasma universal 16S rDNA primer pairs P1/P7 and R16F2n/R16R2. That amplify fragments of 1800 bp and 1250 bp, respectively. Expected fragments were amplified following direct and nested PCR from all symptom-bearing but not from symptomless plants.
Source: https://bsppjournals.onlinelibrary.wiley.com/doi/epdf/10.5197/j.2044-0588.2015.032.017

According to Wikipedia this disease is caused by phytoplasmas or basidiomycetes but can also be caused by fungi and herbicides:

Diseases with symptoms of witches' broom, caused by phytoplasmas or basidiomycetes, are economically important in a number of crop plants, including the cocoa tree Theobroma cacao, jujube (Ziziphus jujuba) and the timber tree Melia azedarach.
Source: https://en.wikipedia.org/wiki/Witch%27s_broom

The most known cause of this disease is the fungi Moniliophthora perniciosa (Stahel) Aime. Other causes are more likely, such as herbicides.

This wikipedia paragraph informs us of how this disease is spread:

Phytoplasmas are pathogens of agriculturally important plants, including coconut, sugarcane, sandalwood, and cannabis, as well as horticultural crops like sweet cherry, peaches, and nectarines. They cause a wide variety of symptoms ranging from mild yellowing, small fruit, and reduced sugar content to death. Phytoplasmas are most prevalent in tropical and subtropical regions. They are transmitted from plant to plant by vectors (normally sap-sucking insects such as leafhoppers) in which they both survive and replicate.

The exact type of phytoplasma is fairly hard to figure out, so I encourage you to post this on https://naturalist.org for scientific attention

There are many types of phytoplasma, here are some examples of Aster Yellows Phytoplasma (Phytoplasma asteris):

https://www.inaturalist.org/photos/88865514, Photo 88865514, (c) Chris Kreussling (Flatbush Gardener), some rights reserved (CC BY-NC), uploaded by Chris Kreussling (Flatbush Gardener) https://www.inaturalist.org/photos/30163460, Photo 30163460, (c) Colin Purrington, all rights reserved, uploaded by Colin Purrington

Here is a picture of the flowering plant Yellow Salsify (Tragopogon dubius), of which the plant in the picture has been identified as:
https://www.inaturalist.org/photos/289034746, Photo 289034746, (c) Hans, some rights reserved (CC BY-NC), uploaded by Hans

Answer 2

Yes, this is yellow salsify but it seems to have contracted a phytoplasma infection that has retarded its normal flower development - and somewhat altered its overall growth habit, causing the blooms to end up halfway between petals and leaves.