https://www.flower-db.com/en/flowers/camellia-japonica-hanaguruma
花車椿	0	0.0%
はなぐるまつばき	0	0.0%
ハナグルマツバキ	0	0.0%

Seems it's known in camellia circles, but the Japanese forms simply don't register. I wouldn't mind if it were dropped.

Some siblings of 花車椿 (which I am guessing we don't want in this dictionary either), with pictures of each:

https://www.omu.ac.jp/bg/info/kaika/entry-24991.html
 ツバキ(天の川)  ツバキ(天人の庵)  ツバキ(弁天椿)
 ツバキ(白錦魚) ツバキ(八朔絞) ツバキ(呼子鳥)   ツバキ(限り)  ツバキ(赤腰蓑)  ツバキ(太平楽)
 ツバキ(玉兎)  ツバキ(沖の浪) ツバキ(源氏唐子) ツバキ(やすらい) 
ツバキ(小紅葉)  ツバキ(都鳥) ツバキ(祇園守)  ツバキ(無類絞)
ツバキ(残雪) ツバキ(天人松島) ツバキ(玉手箱) ツバキ(紅観音)
 ツバキ(紅春) ツバキ(利休絞) ツバキ(花泉砂子)  ツバキ(雪椿) 
ツバキ(雪椿)  ツバキ(千葉椿) ツバキ(荒獅子) ツバキ(蓮上の宝)  ツバキ(白大神楽)  ツバキ(月見車) 
ツバキ(五色散椿)   ツバキ(狂獅子) ツバキ(曇華院散椿) ツバキ(日光)
ツバキ(村娘) ツバキ(東絞) ツバキ(八橋)   ツバキ(紅春) ツバキ(財宝錦) ツバキ(菱唐糸) 
ツバキ(菱柄) ツバキ(縮緬) ツバキ(曙錦)  ツバキ(弁慶) ツバキ(旭の湊) ツバキ(蜑小船) 
 ツバキ(新司錦) ツバキ(暁山) ツバキ(東雲)   ツバキ(蜀紅錦) ツバキ(銀閣寺) ツバキ(袖隠) 
ツバキ(照月) ツバキ(匂吹雪) ツバキ(御所桜) ツバキ(日月星) 
ツバキ(別府) ツバキ(国の光) ツバキ(通小町) ツバキ(妙蓮寺) 
ツバキ(八橋) ツバキ(花車)  ツバキ(光明)   ツバキ(田代)  ツバキ(久留米白波)

Was checking ngrams on 椿 terms.

This is an eminently obscure variety of ツバキ. 
Search "ハナグルマツバキ" in quotes, and all you get is ~6 和英辞典 entries and that's it.
Search "hanakuruma camellia" and you get dictionaries.
Search "花車椿" in quotes and you'll get mostly dictionary references, plus a handful of legitimate entries.

I've included one such entry in the refs, which contains a laundry-list of random ツバキ flower varieties, almost all just as obscure as this one.

I think it's reasonable to have a threshold for inclusion of flower names, and any threshold one might pick, this flower would fall beneath it.  The alternative is to allow thousands of random flower names that don't do anyone any good. 

As a flower, this is also as close to A + B as one could get. This entry is literally "Flower Cart" + "Camellia japonica" = "Flower Cart Camellia japonica". This entry adds no information.

What's particularly amusing is that we don't even have an entry for the real word 花車[はなぐるま] "flower cart". 

In tandem with deleting this, adding a 花車 "flower cart" entry would probably be more useful for everyone.

Strong, strong recommendation to delete this one.

typo, right?

@@ -16 +16 @@
-<gloss>hanakuruma camelia (Camellia japonica var.)</gloss>
+<gloss>hanakuruma camellia (Camellia japonica var.)</gloss>

It's a variety. See: http://www.edrdg.org/wiki/index.php/Editorial_policy#Names_of_biological_species about halfway down.

@@ -9,0 +10,4 @@
+<r_ele>
+<reb>ハナグルマツバキ</reb>
+<re_nokanji/>
+</r_ele>
@@ -12,2 +16 @@
-<gloss>hanakuruma camelia</gloss>
-<gloss>Camellia japonica var.</gloss>
+<gloss>hanakuruma camelia (Camellia japonica var.)</gloss>