Thursday, June 11, 2015

Are Hoya herbaceous perennials ?

In the additional declarations of the phytosanitary certificates should the 45.1 apply to Hoya plants ?

In the Annex IV The 45.1 ( control of Bemisia tabaci ) applies to Herbaceous plants. Herbaceous means plants that are non woody ( non ligneuses ) AND die then restart through cycles.
The Hoya may be non woody but it matters that they are perennial in the sense that they don't die every year or two to restart from the roots. So the 45.1 should not apply.

Also the point 46 is normally mentioned in the declarations and this point  says that the plants are treated to eradicate Bemisia tabaci.
However the 46 says that it applies without prejudice to the requirements applicable to the plants listed in .. 45.1 : the Thai phytosanitary services understand that when eradication of Bemisia tabaci has been done ( 46 ) if the plants are herbaceous, then 45.1 must be mentioned. No problem with that.

So why do some agents seem to opt for  " herbaceous Hoya " whereas these plants do not die and start from their roots or from seeds periodically ?

Perhaps the cause is a confusing concept in the Annex itself : " HERBACEOUS PERENNIAL " at the point 44. The definition is not given by the Annex.
Hence it could mean any plant that is non woody and lives more than two years. So it would apply to the Hoya.
Are Hoya herbaceous perennials  ( herbacees vivaces ) ? No they are not : even if we assume that they are not woody,  herbaceous perennial does not mean any plant that is non woody and lives more than two years. We should understand herbaceous perennial as defined in this article in Wikipedia with the idea of growing season in mind :  " Perennials, especially small flowering plants, that grow and bloom over the spring and summer, die back every autumn and winter, and then return in the spring from their rootstock, are known as herbaceous perennials. " Herbaceous perennial and biennial plants have stems that die at the end of the growing season, but parts of the plant survive under or close to the ground from season to season (for biennials, until the next growing season, when they flower and die). New growth develops from living tissues remaining on or under the ground, including roots, a caudex (a thickened portion of the stem at ground level) or various types of underground stems, such as bulbs, corms, stolons, rhizomes and tubers. Examples of herbaceous biennials include carrot, parsnip and common ragwort; herbaceous perennials include potato, peony, hosta, mint, most ferns and most grasses. By contrast, non-herbaceous perennial plants are woody plants which have stems above ground that remain alive during the dormant season and grow shoots the next year from the above-ground parts – these include trees, shrubs and vines.

In a nutshell :
Herbaceous ( non perennial ) : non woody, dies and restarts from roots or seeds within 1 or 2 years ( ex. carrot )
Herbaceous perennial : non woody, dies and restarts from underground parts and lives more than 2 years ( ex. potato )
Hoya are none of the above, they don't die and restart from roots or seeds so they are not herbaceous. Besides, considered as vines they fall within the concept of woody.

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